<?xml version="1.0" encoding="us-ascii"?>
<!-- Created by Merrill Corporation -->
<!--Generated by IRIS XBRL Generation Engine-->
<link:linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" />
  <link:roleRef roleURI="http://www.veracyte.com/role/DisclosureDebtDetails" xlink:type="simple" xlink:href="vcyt-20140331.xsd#DisclosureDebtDetails" />
  <link:roleRef roleURI="http://www.veracyte.com/role/DisclosureOrganizationAndDescriptionOfBusinessDetails" xlink:type="simple" xlink:href="vcyt-20140331.xsd#DisclosureOrganizationAndDescriptionOfBusinessDetails" />
  <link:roleRef roleURI="http://www.veracyte.com/role/DisclosureStockIncentivePlansDetails3" xlink:type="simple" xlink:href="vcyt-20140331.xsd#DisclosureStockIncentivePlansDetails3" />
  <link:roleRef roleURI="http://www.veracyte.com/role/DisclosureConvertiblePreferredStockWarrantDetails" xlink:type="simple" xlink:href="vcyt-20140331.xsd#DisclosureConvertiblePreferredStockWarrantDetails" />
  <link:roleRef roleURI="http://www.veracyte.com/role/DisclosureConvertiblePreferredStockDetails" xlink:type="simple" xlink:href="vcyt-20140331.xsd#DisclosureConvertiblePreferredStockDetails" />
  <link:roleRef roleURI="http://www.veracyte.com/role/DisclosureStockIncentivePlansDetails5" xlink:type="simple" xlink:href="vcyt-20140331.xsd#DisclosureStockIncentivePlansDetails5" />
  <link:roleRef roleURI="http://www.veracyte.com/role/DisclosureOrganizationAndSummaryOfSignificantAccountingPoliciesDetails2" xlink:type="simple" xlink:href="vcyt-20140331.xsd#DisclosureOrganizationAndSummaryOfSignificantAccountingPoliciesDetails2" />
  <link:roleRef roleURI="http://www.veracyte.com/role/DisclosureBalanceSheetComponentsDetails" xlink:type="simple" xlink:href="vcyt-20140331.xsd#DisclosureBalanceSheetComponentsDetails" />
  <link:roleRef roleURI="http://www.veracyte.com/role/DisclosureStockholdersEquityDetails" xlink:type="simple" xlink:href="vcyt-20140331.xsd#DisclosureStockholdersEquityDetails" />
  <link:roleRef roleURI="http://www.veracyte.com/role/DisclosureIncomeTaxesDetails" xlink:type="simple" xlink:href="vcyt-20140331.xsd#DisclosureIncomeTaxesDetails" />
  <link:roleRef roleURI="http://www.veracyte.com/role/DisclosureIncomeTaxesDetails2" xlink:type="simple" xlink:href="vcyt-20140331.xsd#DisclosureIncomeTaxesDetails2" />
  <link:roleRef roleURI="http://www.veracyte.com/role/DisclosureIncomeTaxesDetails3" xlink:type="simple" xlink:href="vcyt-20140331.xsd#DisclosureIncomeTaxesDetails3" />
  <link:roleRef roleURI="http://www.veracyte.com/role/DisclosureSubsequentEventsDetails" xlink:type="simple" xlink:href="vcyt-20140331.xsd#DisclosureSubsequentEventsDetails" />
  <link:roleRef roleURI="http://www.veracyte.com/role/DisclosureSummaryOfSignificantAccountingPoliciesDetails4" xlink:type="simple" xlink:href="vcyt-20140331.xsd#DisclosureSummaryOfSignificantAccountingPoliciesDetails4" />
  <link:roleRef roleURI="http://www.veracyte.com/role/DisclosureStockIncentivePlansDetails4" xlink:type="simple" xlink:href="vcyt-20140331.xsd#DisclosureStockIncentivePlansDetails4" />
  <link:roleRef roleURI="http://www.veracyte.com/role/DisclosureStockIncentivePlanDetails7" xlink:type="simple" xlink:href="vcyt-20140331.xsd#DisclosureStockIncentivePlanDetails7" />
  <link:roleRef roleURI="http://www.veracyte.com/role/DisclosureGenzymeCopromotionAgreementDetails" xlink:type="simple" xlink:href="vcyt-20140331.xsd#DisclosureGenzymeCopromotionAgreementDetails" />
  <link:roleRef roleURI="http://www.veracyte.com/role/DisclosureThyroidCytologyPartnersDetails" xlink:type="simple" xlink:href="vcyt-20140331.xsd#DisclosureThyroidCytologyPartnersDetails" />
  <link:roleRef roleURI="http://www.veracyte.com/role/DisclosureStockIncentivePlansTables" xlink:type="simple" xlink:href="vcyt-20140331.xsd#DisclosureStockIncentivePlansTables" />
  <link:roleRef roleURI="http://www.veracyte.com/role/DisclosureFairValueMeasurementsDetails" xlink:type="simple" xlink:href="vcyt-20140331.xsd#DisclosureFairValueMeasurementsDetails" />
  <link:roleRef roleURI="http://www.veracyte.com/role/DisclosureFairValueMeasurementsDetails3" xlink:type="simple" xlink:href="vcyt-20140331.xsd#DisclosureFairValueMeasurementsDetails3" />
  <link:roleRef roleURI="http://www.veracyte.com/role/DisclosureFairValueMeasurementsDetails2" xlink:type="simple" xlink:href="vcyt-20140331.xsd#DisclosureFairValueMeasurementsDetails2" />
  <link:roleRef roleURI="http://www.veracyte.com/role/DisclosureStockIncentivePlansDetails2" xlink:type="simple" xlink:href="vcyt-20140331.xsd#DisclosureStockIncentivePlansDetails2" />
  <link:roleRef roleURI="http://www.veracyte.com/role/DisclosureOrganizationAndSummaryOfSignificantAccountingPoliciesDetails" xlink:type="simple" xlink:href="vcyt-20140331.xsd#DisclosureOrganizationAndSummaryOfSignificantAccountingPoliciesDetails" />
  <link:roleRef roleURI="http://www.veracyte.com/role/DisclosureNetLossPerCommonShareDetails" xlink:type="simple" xlink:href="vcyt-20140331.xsd#DisclosureNetLossPerCommonShareDetails" />
  <link:roleRef roleURI="http://www.veracyte.com/role/DisclosureCommitmentsAndContingenciesDetails" xlink:type="simple" xlink:href="vcyt-20140331.xsd#DisclosureCommitmentsAndContingenciesDetails" />
  <link:roleRef roleURI="http://www.veracyte.com/role/StatementsOfStockholdersEquityParenthetical" xlink:type="simple" xlink:href="vcyt-20140331.xsd#StatementsOfStockholdersEquityParenthetical" />
  <link:roleRef roleURI="http://www.veracyte.com/role/StatementsOfStockholdersEquity" xlink:type="simple" xlink:href="vcyt-20140331.xsd#StatementsOfStockholdersEquity" />
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/DisclosureDebtDetails">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems" xlink:title="DebtInstrumentLineItems" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable" xlink:title="DebtInstrumentTable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems" xlink:to="loc_us-gaap_DebtInstrumentTable" xlink:title="Definition : loc_us-gaap_DebtInstrumentLineItems to loc_us-gaap_DebtInstrumentTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis" xlink:title="LongtermDebtTypeAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain" xlink:title="LongtermDebtTypeDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis" xlink:to="loc_us-gaap_LongtermDebtTypeDomain" xlink:title="Definition : loc_us-gaap_LongtermDebtTypeAxis to loc_us-gaap_LongtermDebtTypeDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LineOfCreditMember" xlink:label="loc_us-gaap_LineOfCreditMember" xlink:title="LineOfCreditMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain" xlink:to="loc_us-gaap_LineOfCreditMember" xlink:title="Definition : loc_us-gaap_LongtermDebtTypeDomain to loc_us-gaap_LineOfCreditMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_TermLoanOneMember" xlink:label="loc_vcyt_TermLoanOneMember" xlink:title="TermLoanOneMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditMember" xlink:to="loc_vcyt_TermLoanOneMember" xlink:title="Definition : loc_us-gaap_LineOfCreditMember to loc_vcyt_TermLoanOneMember" xlink:type="arc" use="optional" order="1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable" xlink:to="loc_us-gaap_LongtermDebtTypeAxis" xlink:title="Definition : loc_us-gaap_DebtInstrumentTable to loc_us-gaap_LongtermDebtTypeAxis" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="LongtermDebtTypeDomain_1" xlink:title="LongtermDebtTypeDomain_1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis" xlink:to="LongtermDebtTypeDomain_1" xlink:title="Definition : loc_us-gaap_LongtermDebtTypeAxis to loc_us-gaap_LongtermDebtTypeDomain" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:title="LineOfCreditFacilityMaximumBorrowingCapacity" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:title="Definition : loc_us-gaap_DebtInstrumentLineItems to loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfWarrantOrRightAxis" xlink:label="loc_us-gaap_ClassOfWarrantOrRightAxis" xlink:title="ClassOfWarrantOrRightAxis" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable" xlink:to="loc_us-gaap_ClassOfWarrantOrRightAxis" xlink:title="Definition : loc_us-gaap_DebtInstrumentTable to loc_us-gaap_ClassOfWarrantOrRightAxis" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount" xlink:title="DebtInstrumentFaceAmount" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount" xlink:title="Definition : loc_us-gaap_DebtInstrumentLineItems to loc_us-gaap_DebtInstrumentFaceAmount" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount" xlink:label="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount" xlink:title="DebtInstrumentUnusedBorrowingCapacityAmount" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems" xlink:to="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount" xlink:title="Definition : loc_us-gaap_DebtInstrumentLineItems to loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount" xlink:type="arc" use="optional" order="4" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_DebtInstrumentNumberOfInstallments" xlink:label="loc_vcyt_DebtInstrumentNumberOfInstallments" xlink:title="DebtInstrumentNumberOfInstallments" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems" xlink:to="loc_vcyt_DebtInstrumentNumberOfInstallments" xlink:title="Definition : loc_us-gaap_DebtInstrumentLineItems to loc_vcyt_DebtInstrumentNumberOfInstallments" xlink:type="arc" use="optional" order="5" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_DebtInstrumentPeriodAfterWhichDebtIsRepayable" xlink:label="loc_vcyt_DebtInstrumentPeriodAfterWhichDebtIsRepayable" xlink:title="DebtInstrumentPeriodAfterWhichDebtIsRepayable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems" xlink:to="loc_vcyt_DebtInstrumentPeriodAfterWhichDebtIsRepayable" xlink:title="Definition : loc_us-gaap_DebtInstrumentLineItems to loc_vcyt_DebtInstrumentPeriodAfterWhichDebtIsRepayable" xlink:type="arc" use="optional" order="6" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:title="DebtInstrumentInterestRateStatedPercentage" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:title="Definition : loc_us-gaap_DebtInstrumentLineItems to loc_us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:type="arc" use="optional" order="7" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_DebtInstrumentPenaltyPercentageOnPrepaymentWithinOneYearOfOrigination" xlink:label="loc_vcyt_DebtInstrumentPenaltyPercentageOnPrepaymentWithinOneYearOfOrigination" xlink:title="DebtInstrumentPenaltyPercentageOnPrepaymentWithinOneYearOfOrigination" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems" xlink:to="loc_vcyt_DebtInstrumentPenaltyPercentageOnPrepaymentWithinOneYearOfOrigination" xlink:title="Definition : loc_us-gaap_DebtInstrumentLineItems to loc_vcyt_DebtInstrumentPenaltyPercentageOnPrepaymentWithinOneYearOfOrigination" xlink:type="arc" use="optional" order="8" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_DebtInstrumentPenaltyPercentageOnPrepaymentWithinTwoYearsOfOrigination" xlink:label="loc_vcyt_DebtInstrumentPenaltyPercentageOnPrepaymentWithinTwoYearsOfOrigination" xlink:title="DebtInstrumentPenaltyPercentageOnPrepaymentWithinTwoYearsOfOrigination" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems" xlink:to="loc_vcyt_DebtInstrumentPenaltyPercentageOnPrepaymentWithinTwoYearsOfOrigination" xlink:title="Definition : loc_us-gaap_DebtInstrumentLineItems to loc_vcyt_DebtInstrumentPenaltyPercentageOnPrepaymentWithinTwoYearsOfOrigination" xlink:type="arc" use="optional" order="9" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_DebtInstrumentPenaltyPercentageOnPrepaymentAfterTwoYearsOfOrigination" xlink:label="loc_vcyt_DebtInstrumentPenaltyPercentageOnPrepaymentAfterTwoYearsOfOrigination" xlink:title="DebtInstrumentPenaltyPercentageOnPrepaymentAfterTwoYearsOfOrigination" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems" xlink:to="loc_vcyt_DebtInstrumentPenaltyPercentageOnPrepaymentAfterTwoYearsOfOrigination" xlink:title="Definition : loc_us-gaap_DebtInstrumentLineItems to loc_vcyt_DebtInstrumentPenaltyPercentageOnPrepaymentAfterTwoYearsOfOrigination" xlink:type="arc" use="optional" order="10" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LongTermDebt" xlink:label="loc_us-gaap_LongTermDebt" xlink:title="LongTermDebt" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems" xlink:to="loc_us-gaap_LongTermDebt" xlink:title="Definition : loc_us-gaap_DebtInstrumentLineItems to loc_us-gaap_LongTermDebt" xlink:type="arc" use="optional" order="11" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount" xlink:title="DebtInstrumentCarryingAmount" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount" xlink:title="Definition : loc_us-gaap_DebtInstrumentLineItems to loc_us-gaap_DebtInstrumentCarryingAmount" xlink:type="arc" use="optional" order="12" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DebtInstrumentUnamortizedDiscount" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscount" xlink:title="DebtInstrumentUnamortizedDiscount" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscount" xlink:title="Definition : loc_us-gaap_DebtInstrumentLineItems to loc_us-gaap_DebtInstrumentUnamortizedDiscount" xlink:type="arc" use="optional" order="13" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LongTermDebtCurrent" xlink:label="loc_us-gaap_LongTermDebtCurrent" xlink:title="LongTermDebtCurrent" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems" xlink:to="loc_us-gaap_LongTermDebtCurrent" xlink:title="Definition : loc_us-gaap_DebtInstrumentLineItems to loc_us-gaap_LongTermDebtCurrent" xlink:type="arc" use="optional" order="14" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LongTermDebtNoncurrent" xlink:label="loc_us-gaap_LongTermDebtNoncurrent" xlink:title="LongTermDebtNoncurrent" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems" xlink:to="loc_us-gaap_LongTermDebtNoncurrent" xlink:title="Definition : loc_us-gaap_DebtInstrumentLineItems to loc_us-gaap_LongTermDebtNoncurrent" xlink:type="arc" use="optional" order="15" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_DebtInstrumentEndOfTermPaymentAmount" xlink:label="loc_vcyt_DebtInstrumentEndOfTermPaymentAmount" xlink:title="DebtInstrumentEndOfTermPaymentAmount" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems" xlink:to="loc_vcyt_DebtInstrumentEndOfTermPaymentAmount" xlink:title="Definition : loc_us-gaap_DebtInstrumentLineItems to loc_vcyt_DebtInstrumentEndOfTermPaymentAmount" xlink:type="arc" use="optional" order="16" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_DebtInstrumentEndOfTermPaymentAsPercentageOfTotalOutstandingPrincipal" xlink:label="loc_vcyt_DebtInstrumentEndOfTermPaymentAsPercentageOfTotalOutstandingPrincipal" xlink:title="DebtInstrumentEndOfTermPaymentAsPercentageOfTotalOutstandingPrincipal" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems" xlink:to="loc_vcyt_DebtInstrumentEndOfTermPaymentAsPercentageOfTotalOutstandingPrincipal" xlink:title="Definition : loc_us-gaap_DebtInstrumentLineItems to loc_vcyt_DebtInstrumentEndOfTermPaymentAsPercentageOfTotalOutstandingPrincipal" xlink:type="arc" use="optional" order="17" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_InterestExpenseDebt" xlink:label="loc_us-gaap_InterestExpenseDebt" xlink:title="InterestExpenseDebt" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems" xlink:to="loc_us-gaap_InterestExpenseDebt" xlink:title="Definition : loc_us-gaap_DebtInstrumentLineItems to loc_us-gaap_InterestExpenseDebt" xlink:type="arc" use="optional" order="18" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_InterestExpenseDebtExcludingAmortization" xlink:label="loc_us-gaap_InterestExpenseDebtExcludingAmortization" xlink:title="InterestExpenseDebtExcludingAmortization" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems" xlink:to="loc_us-gaap_InterestExpenseDebtExcludingAmortization" xlink:title="Definition : loc_us-gaap_DebtInstrumentLineItems to loc_us-gaap_InterestExpenseDebtExcludingAmortization" xlink:type="arc" use="optional" order="19" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DepreciationAmortizationAndAccretionNet" xlink:label="loc_us-gaap_DepreciationAmortizationAndAccretionNet" xlink:title="DepreciationAmortizationAndAccretionNet" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems" xlink:to="loc_us-gaap_DepreciationAmortizationAndAccretionNet" xlink:title="Definition : loc_us-gaap_DebtInstrumentLineItems to loc_us-gaap_DepreciationAmortizationAndAccretionNet" xlink:type="arc" use="optional" order="20" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain" xlink:title="ClassOfWarrantOrRightDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain" xlink:title="Definition : loc_us-gaap_ClassOfWarrantOrRightAxis to loc_us-gaap_ClassOfWarrantOrRightDomain" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ConvertiblePreferredStockWarrantsMember" xlink:label="loc_vcyt_ConvertiblePreferredStockWarrantsMember" xlink:title="ConvertiblePreferredStockWarrantsMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain" xlink:to="loc_vcyt_ConvertiblePreferredStockWarrantsMember" xlink:title="Definition : loc_us-gaap_ClassOfWarrantOrRightDomain to loc_vcyt_ConvertiblePreferredStockWarrantsMember" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ClassOfWarrantOrRightNumberOfSecuritiesForWhichWarrantsWillBecomeExercisableInEventOfConversionOfPreferredStockIntoCommonStock" xlink:label="loc_vcyt_ClassOfWarrantOrRightNumberOfSecuritiesForWhichWarrantsWillBecomeExercisableInEventOfConversionOfPreferredStockIntoCommonStock" xlink:title="ClassOfWarrantOrRightNumberOfSecuritiesForWhichWarrantsWillBecomeExercisableInEventOfConversionOfPreferredStockIntoCommonStock" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems" xlink:to="loc_vcyt_ClassOfWarrantOrRightNumberOfSecuritiesForWhichWarrantsWillBecomeExercisableInEventOfConversionOfPreferredStockIntoCommonStock" xlink:title="Definition : loc_us-gaap_DebtInstrumentLineItems to loc_vcyt_ClassOfWarrantOrRightNumberOfSecuritiesForWhichWarrantsWillBecomeExercisableInEventOfConversionOfPreferredStockIntoCommonStock" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="ClassOfWarrantOrRightDomain_2" xlink:title="ClassOfWarrantOrRightDomain_2" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis" xlink:to="ClassOfWarrantOrRightDomain_2" xlink:title="Definition : loc_us-gaap_ClassOfWarrantOrRightAxis to loc_us-gaap_ClassOfWarrantOrRightDomain" xlink:type="arc" use="optional" order="8001" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DerivativeLiabilitiesCurrent" xlink:label="loc_us-gaap_DerivativeLiabilitiesCurrent" xlink:title="DerivativeLiabilitiesCurrent" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems" xlink:to="loc_us-gaap_DerivativeLiabilitiesCurrent" xlink:title="Definition : loc_us-gaap_DebtInstrumentLineItems to loc_us-gaap_DerivativeLiabilitiesCurrent" xlink:type="arc" use="optional" order="8001" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_DebtInstrumentRemainingDiscountAmortizationPeriod" xlink:label="loc_vcyt_DebtInstrumentRemainingDiscountAmortizationPeriod" xlink:title="DebtInstrumentRemainingDiscountAmortizationPeriod" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems" xlink:to="loc_vcyt_DebtInstrumentRemainingDiscountAmortizationPeriod" xlink:title="Definition : loc_us-gaap_DebtInstrumentLineItems to loc_vcyt_DebtInstrumentRemainingDiscountAmortizationPeriod" xlink:type="arc" use="optional" order="8002" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/DisclosureOrganizationAndDescriptionOfBusinessDetails">
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems" xlink:label="loc_vcyt_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems" xlink:title="OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_OrganizationConsolidationAndPresentationOfFinancialStatementsTable" xlink:label="loc_vcyt_OrganizationConsolidationAndPresentationOfFinancialStatementsTable" xlink:title="OrganizationConsolidationAndPresentationOfFinancialStatementsTable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_vcyt_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems" xlink:to="loc_vcyt_OrganizationConsolidationAndPresentationOfFinancialStatementsTable" xlink:title="Definition : loc_vcyt_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems to loc_vcyt_OrganizationConsolidationAndPresentationOfFinancialStatementsTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis" xlink:title="StatementEquityComponentsAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain" xlink:title="EquityComponentDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis" xlink:to="loc_us-gaap_EquityComponentDomain" xlink:title="Definition : loc_us-gaap_StatementEquityComponentsAxis to loc_us-gaap_EquityComponentDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember" xlink:title="CommonStockMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain" xlink:to="loc_us-gaap_CommonStockMember" xlink:title="Definition : loc_us-gaap_EquityComponentDomain to loc_us-gaap_CommonStockMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromIssuanceOrSaleOfEquityAbstract" xlink:label="loc_us-gaap_ProceedsFromIssuanceOrSaleOfEquityAbstract" xlink:title="ProceedsFromIssuanceOrSaleOfEquityAbstract" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockholdersEquityNoteStockSplitConversionRatio1" xlink:label="loc_us-gaap_StockholdersEquityNoteStockSplitConversionRatio1" xlink:title="StockholdersEquityNoteStockSplitConversionRatio1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProceedsFromIssuanceOrSaleOfEquityAbstract" xlink:to="loc_us-gaap_StockholdersEquityNoteStockSplitConversionRatio1" xlink:title="Definition : loc_us-gaap_ProceedsFromIssuanceOrSaleOfEquityAbstract to loc_us-gaap_StockholdersEquityNoteStockSplitConversionRatio1" xlink:type="arc" use="optional" order="1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_vcyt_OrganizationConsolidationAndPresentationOfFinancialStatementsTable" xlink:to="loc_us-gaap_StatementEquityComponentsAxis" xlink:title="Definition : loc_vcyt_OrganizationConsolidationAndPresentationOfFinancialStatementsTable to loc_us-gaap_StatementEquityComponentsAxis" xlink:type="arc" use="optional" order="1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_vcyt_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems" xlink:to="loc_us-gaap_ProceedsFromIssuanceOrSaleOfEquityAbstract" xlink:title="Definition : loc_vcyt_OrganizationConsolidationAndPresentationOfFinancialStatementsLineItems to loc_us-gaap_ProceedsFromIssuanceOrSaleOfEquityAbstract" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion" xlink:label="loc_us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion" xlink:title="ConvertiblePreferredStockSharesIssuedUponConversion" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProceedsFromIssuanceOrSaleOfEquityAbstract" xlink:to="loc_us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion" xlink:title="Definition : loc_us-gaap_ProceedsFromIssuanceOrSaleOfEquityAbstract to loc_us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:title="StockIssuedDuringPeriodSharesNewIssues" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProceedsFromIssuanceOrSaleOfEquityAbstract" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:title="Definition : loc_us-gaap_ProceedsFromIssuanceOrSaleOfEquityAbstract to loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ProceedsFromIssuanceInitialPublicOfferingNet" xlink:label="loc_vcyt_ProceedsFromIssuanceInitialPublicOfferingNet" xlink:title="ProceedsFromIssuanceInitialPublicOfferingNet" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProceedsFromIssuanceOrSaleOfEquityAbstract" xlink:to="loc_vcyt_ProceedsFromIssuanceInitialPublicOfferingNet" xlink:title="Definition : loc_us-gaap_ProceedsFromIssuanceOrSaleOfEquityAbstract to loc_vcyt_ProceedsFromIssuanceInitialPublicOfferingNet" xlink:type="arc" use="optional" order="5" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_UnderwritingDiscountsAndCommissions" xlink:label="loc_vcyt_UnderwritingDiscountsAndCommissions" xlink:title="UnderwritingDiscountsAndCommissions" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProceedsFromIssuanceOrSaleOfEquityAbstract" xlink:to="loc_vcyt_UnderwritingDiscountsAndCommissions" xlink:title="Definition : loc_us-gaap_ProceedsFromIssuanceOrSaleOfEquityAbstract to loc_vcyt_UnderwritingDiscountsAndCommissions" xlink:type="arc" use="optional" order="6" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_OfferingExpenses" xlink:label="loc_vcyt_OfferingExpenses" xlink:title="OfferingExpenses" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProceedsFromIssuanceOrSaleOfEquityAbstract" xlink:to="loc_vcyt_OfferingExpenses" xlink:title="Definition : loc_us-gaap_ProceedsFromIssuanceOrSaleOfEquityAbstract to loc_vcyt_OfferingExpenses" xlink:type="arc" use="optional" order="7" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:title="StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProceedsFromIssuanceOrSaleOfEquityAbstract" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:title="Definition : loc_us-gaap_ProceedsFromIssuanceOrSaleOfEquityAbstract to loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:type="arc" use="optional" order="8" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/DisclosureStockIncentivePlansDetails3">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:title="ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:title="ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems to loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis" xlink:title="AwardTypeAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:title="ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:title="Definition : loc_us-gaap_AwardTypeAxis to loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember" xlink:title="EmployeeStockOptionMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaap_EmployeeStockOptionMember" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain to loc_us-gaap_EmployeeStockOptionMember" xlink:type="arc" use="optional" order="1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="loc_us-gaap_AwardTypeAxis" xlink:title="Definition : loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable to loc_us-gaap_AwardTypeAxis" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1" xlink:title="SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems to loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis" xlink:title="StatementEquityComponentsAxis" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="loc_us-gaap_StatementEquityComponentsAxis" xlink:title="Definition : loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable to loc_us-gaap_StatementEquityComponentsAxis" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageGrantDateFairValue" xlink:title="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageGrantDateFairValue" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageGrantDateFairValue" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems to loc_vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageGrantDateFairValue" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:title="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems to loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:type="arc" use="optional" order="4" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain" xlink:title="EquityComponentDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis" xlink:to="loc_us-gaap_EquityComponentDomain" xlink:title="Definition : loc_us-gaap_StatementEquityComponentsAxis to loc_us-gaap_EquityComponentDomain" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember" xlink:title="CommonStockMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain" xlink:to="loc_us-gaap_CommonStockMember" xlink:title="Definition : loc_us-gaap_EquityComponentDomain to loc_us-gaap_CommonStockMember" xlink:type="arc" use="optional" order="8000" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/DisclosureConvertiblePreferredStockWarrantDetails">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfWarrantOrRightLineItems" xlink:label="loc_us-gaap_ClassOfWarrantOrRightLineItems" xlink:title="ClassOfWarrantOrRightLineItems" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfWarrantOrRightTable" xlink:label="loc_us-gaap_ClassOfWarrantOrRightTable" xlink:title="ClassOfWarrantOrRightTable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems" xlink:to="loc_us-gaap_ClassOfWarrantOrRightTable" xlink:title="Definition : loc_us-gaap_ClassOfWarrantOrRightLineItems to loc_us-gaap_ClassOfWarrantOrRightTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfWarrantOrRightAxis" xlink:label="loc_us-gaap_ClassOfWarrantOrRightAxis" xlink:title="ClassOfWarrantOrRightAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain" xlink:title="ClassOfWarrantOrRightDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain" xlink:title="Definition : loc_us-gaap_ClassOfWarrantOrRightAxis to loc_us-gaap_ClassOfWarrantOrRightDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ConvertiblePreferredStockWarrantsMember" xlink:label="loc_vcyt_ConvertiblePreferredStockWarrantsMember" xlink:title="ConvertiblePreferredStockWarrantsMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain" xlink:to="loc_vcyt_ConvertiblePreferredStockWarrantsMember" xlink:title="Definition : loc_us-gaap_ClassOfWarrantOrRightDomain to loc_vcyt_ConvertiblePreferredStockWarrantsMember" xlink:type="arc" use="optional" order="1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfWarrantOrRightTable" xlink:to="loc_us-gaap_ClassOfWarrantOrRightAxis" xlink:title="Definition : loc_us-gaap_ClassOfWarrantOrRightTable to loc_us-gaap_ClassOfWarrantOrRightAxis" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight" xlink:label="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight" xlink:title="ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems" xlink:to="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight" xlink:title="Definition : loc_us-gaap_ClassOfWarrantOrRightLineItems to loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis" xlink:title="RangeAxis" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfWarrantOrRightTable" xlink:to="loc_us-gaap_RangeAxis" xlink:title="Definition : loc_us-gaap_ClassOfWarrantOrRightTable to loc_us-gaap_RangeAxis" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ConvertiblePreferredStockOriginalIssuePrice" xlink:label="loc_vcyt_ConvertiblePreferredStockOriginalIssuePrice" xlink:title="ConvertiblePreferredStockOriginalIssuePrice" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems" xlink:to="loc_vcyt_ConvertiblePreferredStockOriginalIssuePrice" xlink:title="Definition : loc_us-gaap_ClassOfWarrantOrRightLineItems to loc_vcyt_ConvertiblePreferredStockOriginalIssuePrice" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis" xlink:title="StatementClassOfStockAxis" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfWarrantOrRightTable" xlink:to="loc_us-gaap_StatementClassOfStockAxis" xlink:title="Definition : loc_us-gaap_ClassOfWarrantOrRightTable to loc_us-gaap_StatementClassOfStockAxis" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount" xlink:title="DebtInstrumentFaceAmount" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount" xlink:title="Definition : loc_us-gaap_ClassOfWarrantOrRightLineItems to loc_us-gaap_DebtInstrumentFaceAmount" xlink:type="arc" use="optional" order="4" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis" xlink:title="SubsequentEventTypeAxis" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfWarrantOrRightTable" xlink:to="loc_us-gaap_SubsequentEventTypeAxis" xlink:title="Definition : loc_us-gaap_ClassOfWarrantOrRightTable to loc_us-gaap_SubsequentEventTypeAxis" xlink:type="arc" use="optional" order="4" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ClassOfWarrantOrRightNumberOfSecuritiesForWhichWarrantsBecameExercisable" xlink:label="loc_vcyt_ClassOfWarrantOrRightNumberOfSecuritiesForWhichWarrantsBecameExercisable" xlink:title="ClassOfWarrantOrRightNumberOfSecuritiesForWhichWarrantsBecameExercisable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems" xlink:to="loc_vcyt_ClassOfWarrantOrRightNumberOfSecuritiesForWhichWarrantsBecameExercisable" xlink:title="Definition : loc_us-gaap_ClassOfWarrantOrRightLineItems to loc_vcyt_ClassOfWarrantOrRightNumberOfSecuritiesForWhichWarrantsBecameExercisable" xlink:type="arc" use="optional" order="5" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis" xlink:title="StatementEquityComponentsAxis" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfWarrantOrRightTable" xlink:to="loc_us-gaap_StatementEquityComponentsAxis" xlink:title="Definition : loc_us-gaap_ClassOfWarrantOrRightTable to loc_us-gaap_StatementEquityComponentsAxis" xlink:type="arc" use="optional" order="5" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_StockIssuedDuringPeriodSharesWarrantsExercised" xlink:label="loc_vcyt_StockIssuedDuringPeriodSharesWarrantsExercised" xlink:title="StockIssuedDuringPeriodSharesWarrantsExercised" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems" xlink:to="loc_vcyt_StockIssuedDuringPeriodSharesWarrantsExercised" xlink:title="Definition : loc_us-gaap_ClassOfWarrantOrRightLineItems to loc_vcyt_StockIssuedDuringPeriodSharesWarrantsExercised" xlink:type="arc" use="optional" order="6" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain" xlink:title="EquityComponentDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis" xlink:to="loc_us-gaap_EquityComponentDomain" xlink:title="Definition : loc_us-gaap_StatementEquityComponentsAxis to loc_us-gaap_EquityComponentDomain" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember" xlink:title="RangeMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis" xlink:to="loc_us-gaap_RangeMember" xlink:title="Definition : loc_us-gaap_RangeAxis to loc_us-gaap_RangeMember" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain" xlink:title="ClassOfStockDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis" xlink:to="loc_us-gaap_ClassOfStockDomain" xlink:title="Definition : loc_us-gaap_StatementClassOfStockAxis to loc_us-gaap_ClassOfStockDomain" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain" xlink:title="SubsequentEventTypeDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis" xlink:to="loc_us-gaap_SubsequentEventTypeDomain" xlink:title="Definition : loc_us-gaap_SubsequentEventTypeAxis to loc_us-gaap_SubsequentEventTypeDomain" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_CommonStockWarrantsMember" xlink:label="loc_vcyt_CommonStockWarrantsMember" xlink:title="CommonStockWarrantsMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain" xlink:to="loc_vcyt_CommonStockWarrantsMember" xlink:title="Definition : loc_us-gaap_ClassOfWarrantOrRightDomain to loc_vcyt_CommonStockWarrantsMember" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember" xlink:title="CommonStockMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain" xlink:to="loc_us-gaap_CommonStockMember" xlink:title="Definition : loc_us-gaap_EquityComponentDomain to loc_us-gaap_CommonStockMember" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember" xlink:title="MaximumMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember" xlink:to="loc_us-gaap_MaximumMember" xlink:title="Definition : loc_us-gaap_RangeMember to loc_us-gaap_MaximumMember" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_SeriesCConvertiblePreferredStockMember" xlink:label="loc_vcyt_SeriesCConvertiblePreferredStockMember" xlink:title="SeriesCConvertiblePreferredStockMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain" xlink:to="loc_vcyt_SeriesCConvertiblePreferredStockMember" xlink:title="Definition : loc_us-gaap_ClassOfStockDomain to loc_vcyt_SeriesCConvertiblePreferredStockMember" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaap_SubsequentEventMember" xlink:title="SubsequentEventMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain" xlink:to="loc_us-gaap_SubsequentEventMember" xlink:title="Definition : loc_us-gaap_SubsequentEventTypeDomain to loc_us-gaap_SubsequentEventMember" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ClassOfWarrantOrRightNumberOfSecuritiesForWhichWarrantsMayBecomeExercisable" xlink:label="loc_vcyt_ClassOfWarrantOrRightNumberOfSecuritiesForWhichWarrantsMayBecomeExercisable" xlink:title="ClassOfWarrantOrRightNumberOfSecuritiesForWhichWarrantsMayBecomeExercisable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems" xlink:to="loc_vcyt_ClassOfWarrantOrRightNumberOfSecuritiesForWhichWarrantsMayBecomeExercisable" xlink:title="Definition : loc_us-gaap_ClassOfWarrantOrRightLineItems to loc_vcyt_ClassOfWarrantOrRightNumberOfSecuritiesForWhichWarrantsMayBecomeExercisable" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract" xlink:label="loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract" xlink:title="FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueAssumptionsExpectedTerm" xlink:label="loc_us-gaap_FairValueAssumptionsExpectedTerm" xlink:title="FairValueAssumptionsExpectedTerm" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract" xlink:to="loc_us-gaap_FairValueAssumptionsExpectedTerm" xlink:title="Definition : loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract to loc_us-gaap_FairValueAssumptionsExpectedTerm" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ClassOfWarrantOrRightTermOfWarrantsOrRights" xlink:label="loc_vcyt_ClassOfWarrantOrRightTermOfWarrantsOrRights" xlink:title="ClassOfWarrantOrRightTermOfWarrantsOrRights" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems" xlink:to="loc_vcyt_ClassOfWarrantOrRightTermOfWarrantsOrRights" xlink:title="Definition : loc_us-gaap_ClassOfWarrantOrRightLineItems to loc_vcyt_ClassOfWarrantOrRightTermOfWarrantsOrRights" xlink:type="arc" use="optional" order="8001" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueAssumptionsRiskFreeInterestRate" xlink:label="loc_us-gaap_FairValueAssumptionsRiskFreeInterestRate" xlink:title="FairValueAssumptionsRiskFreeInterestRate" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract" xlink:to="loc_us-gaap_FairValueAssumptionsRiskFreeInterestRate" xlink:title="Definition : loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract to loc_us-gaap_FairValueAssumptionsRiskFreeInterestRate" xlink:type="arc" use="optional" order="8001" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ClassOfWarrantOrRightPotentialNumberOfAggregateSecuritiesExercisable" xlink:label="loc_vcyt_ClassOfWarrantOrRightPotentialNumberOfAggregateSecuritiesExercisable" xlink:title="ClassOfWarrantOrRightPotentialNumberOfAggregateSecuritiesExercisable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems" xlink:to="loc_vcyt_ClassOfWarrantOrRightPotentialNumberOfAggregateSecuritiesExercisable" xlink:title="Definition : loc_us-gaap_ClassOfWarrantOrRightLineItems to loc_vcyt_ClassOfWarrantOrRightPotentialNumberOfAggregateSecuritiesExercisable" xlink:type="arc" use="optional" order="8002" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueAssumptionsExpectedVolatilityRate" xlink:label="loc_us-gaap_FairValueAssumptionsExpectedVolatilityRate" xlink:title="FairValueAssumptionsExpectedVolatilityRate" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract" xlink:to="loc_us-gaap_FairValueAssumptionsExpectedVolatilityRate" xlink:title="Definition : loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract to loc_us-gaap_FairValueAssumptionsExpectedVolatilityRate" xlink:type="arc" use="optional" order="8002" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DerivativeLiabilitiesCurrent" xlink:label="loc_us-gaap_DerivativeLiabilitiesCurrent" xlink:title="DerivativeLiabilitiesCurrent" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems" xlink:to="loc_us-gaap_DerivativeLiabilitiesCurrent" xlink:title="Definition : loc_us-gaap_ClassOfWarrantOrRightLineItems to loc_us-gaap_DerivativeLiabilitiesCurrent" xlink:type="arc" use="optional" order="8003" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueAssumptionsExpectedDividendRate" xlink:label="loc_us-gaap_FairValueAssumptionsExpectedDividendRate" xlink:title="FairValueAssumptionsExpectedDividendRate" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract" xlink:to="loc_us-gaap_FairValueAssumptionsExpectedDividendRate" xlink:title="Definition : loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract to loc_us-gaap_FairValueAssumptionsExpectedDividendRate" xlink:type="arc" use="optional" order="8003" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems" xlink:to="loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract" xlink:title="Definition : loc_us-gaap_ClassOfWarrantOrRightLineItems to loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract" xlink:type="arc" use="optional" order="8004" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights" xlink:label="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights" xlink:title="ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems" xlink:to="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights" xlink:title="Definition : loc_us-gaap_ClassOfWarrantOrRightLineItems to loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights" xlink:type="arc" use="optional" order="8005" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/DisclosureConvertiblePreferredStockDetails">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TemporaryEquityLineItems" xlink:label="loc_us-gaap_TemporaryEquityLineItems" xlink:title="TemporaryEquityLineItems" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TemporaryEquityByClassOfStockTable" xlink:label="loc_us-gaap_TemporaryEquityByClassOfStockTable" xlink:title="TemporaryEquityByClassOfStockTable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_TemporaryEquityLineItems" xlink:to="loc_us-gaap_TemporaryEquityByClassOfStockTable" xlink:title="Definition : loc_us-gaap_TemporaryEquityLineItems to loc_us-gaap_TemporaryEquityByClassOfStockTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis" xlink:title="StatementClassOfStockAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain" xlink:title="ClassOfStockDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis" xlink:to="loc_us-gaap_ClassOfStockDomain" xlink:title="Definition : loc_us-gaap_StatementClassOfStockAxis to loc_us-gaap_ClassOfStockDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueByLiabilityClassAxis" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis" xlink:title="FairValueByLiabilityClassAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:title="FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:title="Definition : loc_us-gaap_FairValueByLiabilityClassAxis to loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_SeriesAConvertiblePreferredStockMember" xlink:label="loc_vcyt_SeriesAConvertiblePreferredStockMember" xlink:title="SeriesAConvertiblePreferredStockMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain" xlink:to="loc_vcyt_SeriesAConvertiblePreferredStockMember" xlink:title="Definition : loc_us-gaap_ClassOfStockDomain to loc_vcyt_SeriesAConvertiblePreferredStockMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract" xlink:label="loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract" xlink:title="FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_FairValueAssumptionsProbabilityOfSuccessOfSecondTrancheOfConvertiblePreferredStock" xlink:label="loc_vcyt_FairValueAssumptionsProbabilityOfSuccessOfSecondTrancheOfConvertiblePreferredStock" xlink:title="FairValueAssumptionsProbabilityOfSuccessOfSecondTrancheOfConvertiblePreferredStock" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract" xlink:to="loc_vcyt_FairValueAssumptionsProbabilityOfSuccessOfSecondTrancheOfConvertiblePreferredStock" xlink:title="Definition : loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract to loc_vcyt_FairValueAssumptionsProbabilityOfSuccessOfSecondTrancheOfConvertiblePreferredStock" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_DerivativeFinancialInstrumentsLiabilitiesPreferredStockLiabilityMember" xlink:label="loc_vcyt_DerivativeFinancialInstrumentsLiabilitiesPreferredStockLiabilityMember" xlink:title="DerivativeFinancialInstrumentsLiabilitiesPreferredStockLiabilityMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:to="loc_vcyt_DerivativeFinancialInstrumentsLiabilitiesPreferredStockLiabilityMember" xlink:title="Definition : loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain to loc_vcyt_DerivativeFinancialInstrumentsLiabilitiesPreferredStockLiabilityMember" xlink:type="arc" use="optional" order="1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_TemporaryEquityByClassOfStockTable" xlink:to="loc_us-gaap_StatementClassOfStockAxis" xlink:title="Definition : loc_us-gaap_TemporaryEquityByClassOfStockTable to loc_us-gaap_StatementClassOfStockAxis" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="ClassOfStockDomain_1" xlink:title="ClassOfStockDomain_1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis" xlink:to="ClassOfStockDomain_1" xlink:title="Definition : loc_us-gaap_StatementClassOfStockAxis to loc_us-gaap_ClassOfStockDomain" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_SeriesBConvertiblePreferredStockMember" xlink:label="loc_vcyt_SeriesBConvertiblePreferredStockMember" xlink:title="SeriesBConvertiblePreferredStockMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain" xlink:to="loc_vcyt_SeriesBConvertiblePreferredStockMember" xlink:title="Definition : loc_us-gaap_ClassOfStockDomain to loc_vcyt_SeriesBConvertiblePreferredStockMember" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ConversionOfStockSharesConverted1" xlink:label="loc_us-gaap_ConversionOfStockSharesConverted1" xlink:title="ConversionOfStockSharesConverted1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems" xlink:to="loc_us-gaap_ConversionOfStockSharesConverted1" xlink:title="Definition : loc_us-gaap_TemporaryEquityLineItems to loc_us-gaap_ConversionOfStockSharesConverted1" xlink:type="arc" use="optional" order="2" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_TemporaryEquityByClassOfStockTable" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis" xlink:title="Definition : loc_us-gaap_TemporaryEquityByClassOfStockTable to loc_us-gaap_FairValueByLiabilityClassAxis" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_SeriesCConvertiblePreferredStockMember" xlink:label="loc_vcyt_SeriesCConvertiblePreferredStockMember" xlink:title="SeriesCConvertiblePreferredStockMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain" xlink:to="loc_vcyt_SeriesCConvertiblePreferredStockMember" xlink:title="Definition : loc_us-gaap_ClassOfStockDomain to loc_vcyt_SeriesCConvertiblePreferredStockMember" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueAssumptionsExpectedTerm" xlink:label="loc_us-gaap_FairValueAssumptionsExpectedTerm" xlink:title="FairValueAssumptionsExpectedTerm" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract" xlink:to="loc_us-gaap_FairValueAssumptionsExpectedTerm" xlink:title="Definition : loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract to loc_us-gaap_FairValueAssumptionsExpectedTerm" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:title="StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:title="Definition : loc_us-gaap_TemporaryEquityLineItems to loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueAssumptionsExpectedVolatilityRate" xlink:label="loc_us-gaap_FairValueAssumptionsExpectedVolatilityRate" xlink:title="FairValueAssumptionsExpectedVolatilityRate" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract" xlink:to="loc_us-gaap_FairValueAssumptionsExpectedVolatilityRate" xlink:title="Definition : loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract to loc_us-gaap_FairValueAssumptionsExpectedVolatilityRate" xlink:type="arc" use="optional" order="4" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TemporaryEquitySharesAuthorized" xlink:label="loc_us-gaap_TemporaryEquitySharesAuthorized" xlink:title="TemporaryEquitySharesAuthorized" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems" xlink:to="loc_us-gaap_TemporaryEquitySharesAuthorized" xlink:title="Definition : loc_us-gaap_TemporaryEquityLineItems to loc_us-gaap_TemporaryEquitySharesAuthorized" xlink:type="arc" use="optional" order="4" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TemporaryEquitySharesIssued" xlink:label="loc_us-gaap_TemporaryEquitySharesIssued" xlink:title="TemporaryEquitySharesIssued" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems" xlink:to="loc_us-gaap_TemporaryEquitySharesIssued" xlink:title="Definition : loc_us-gaap_TemporaryEquityLineItems to loc_us-gaap_TemporaryEquitySharesIssued" xlink:type="arc" use="optional" order="5" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TemporaryEquitySharesOutstanding" xlink:label="loc_us-gaap_TemporaryEquitySharesOutstanding" xlink:title="TemporaryEquitySharesOutstanding" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems" xlink:to="loc_us-gaap_TemporaryEquitySharesOutstanding" xlink:title="Definition : loc_us-gaap_TemporaryEquityLineItems to loc_us-gaap_TemporaryEquitySharesOutstanding" xlink:type="arc" use="optional" order="6" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TemporaryEquityLiquidationPreference" xlink:label="loc_us-gaap_TemporaryEquityLiquidationPreference" xlink:title="TemporaryEquityLiquidationPreference" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems" xlink:to="loc_us-gaap_TemporaryEquityLiquidationPreference" xlink:title="Definition : loc_us-gaap_TemporaryEquityLineItems to loc_us-gaap_TemporaryEquityLiquidationPreference" xlink:type="arc" use="optional" order="7" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_NetProceedsFromIssuanceOfRedeemableConvertiblePreferredStock" xlink:label="loc_vcyt_NetProceedsFromIssuanceOfRedeemableConvertiblePreferredStock" xlink:title="NetProceedsFromIssuanceOfRedeemableConvertiblePreferredStock" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems" xlink:to="loc_vcyt_NetProceedsFromIssuanceOfRedeemableConvertiblePreferredStock" xlink:title="Definition : loc_us-gaap_TemporaryEquityLineItems to loc_vcyt_NetProceedsFromIssuanceOfRedeemableConvertiblePreferredStock" xlink:type="arc" use="optional" order="8" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_TemporaryEquityStockAuthorizedToBeIssuedAndSold" xlink:label="loc_vcyt_TemporaryEquityStockAuthorizedToBeIssuedAndSold" xlink:title="TemporaryEquityStockAuthorizedToBeIssuedAndSold" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems" xlink:to="loc_vcyt_TemporaryEquityStockAuthorizedToBeIssuedAndSold" xlink:title="Definition : loc_us-gaap_TemporaryEquityLineItems to loc_vcyt_TemporaryEquityStockAuthorizedToBeIssuedAndSold" xlink:type="arc" use="optional" order="9" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_NumberOfClosings" xlink:label="loc_vcyt_NumberOfClosings" xlink:title="NumberOfClosings" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems" xlink:to="loc_vcyt_NumberOfClosings" xlink:title="Definition : loc_us-gaap_TemporaryEquityLineItems to loc_vcyt_NumberOfClosings" xlink:type="arc" use="optional" order="10" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_TemporaryEquityNumberOfSharesThatMayBeSoldInInitialPurchase" xlink:label="loc_vcyt_TemporaryEquityNumberOfSharesThatMayBeSoldInInitialPurchase" xlink:title="TemporaryEquityNumberOfSharesThatMayBeSoldInInitialPurchase" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems" xlink:to="loc_vcyt_TemporaryEquityNumberOfSharesThatMayBeSoldInInitialPurchase" xlink:title="Definition : loc_us-gaap_TemporaryEquityLineItems to loc_vcyt_TemporaryEquityNumberOfSharesThatMayBeSoldInInitialPurchase" xlink:type="arc" use="optional" order="11" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_TemporaryEquityNumberOfSharesThatMayBeSoldInSecondClosing" xlink:label="loc_vcyt_TemporaryEquityNumberOfSharesThatMayBeSoldInSecondClosing" xlink:title="TemporaryEquityNumberOfSharesThatMayBeSoldInSecondClosing" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems" xlink:to="loc_vcyt_TemporaryEquityNumberOfSharesThatMayBeSoldInSecondClosing" xlink:title="Definition : loc_us-gaap_TemporaryEquityLineItems to loc_vcyt_TemporaryEquityNumberOfSharesThatMayBeSoldInSecondClosing" xlink:type="arc" use="optional" order="12" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_TemporaryEquityNumberOfSharesThatMayBeSoldInAdditionalClosings" xlink:label="loc_vcyt_TemporaryEquityNumberOfSharesThatMayBeSoldInAdditionalClosings" xlink:title="TemporaryEquityNumberOfSharesThatMayBeSoldInAdditionalClosings" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems" xlink:to="loc_vcyt_TemporaryEquityNumberOfSharesThatMayBeSoldInAdditionalClosings" xlink:title="Definition : loc_us-gaap_TemporaryEquityLineItems to loc_vcyt_TemporaryEquityNumberOfSharesThatMayBeSoldInAdditionalClosings" xlink:type="arc" use="optional" order="13" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_NumberOfAdditionalClosings" xlink:label="loc_vcyt_NumberOfAdditionalClosings" xlink:title="NumberOfAdditionalClosings" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems" xlink:to="loc_vcyt_NumberOfAdditionalClosings" xlink:title="Definition : loc_us-gaap_TemporaryEquityLineItems to loc_vcyt_NumberOfAdditionalClosings" xlink:type="arc" use="optional" order="14" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_TemporaryEquityStockIssuedDuringPeriodShares" xlink:label="loc_vcyt_TemporaryEquityStockIssuedDuringPeriodShares" xlink:title="TemporaryEquityStockIssuedDuringPeriodShares" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems" xlink:to="loc_vcyt_TemporaryEquityStockIssuedDuringPeriodShares" xlink:title="Definition : loc_us-gaap_TemporaryEquityLineItems to loc_vcyt_TemporaryEquityStockIssuedDuringPeriodShares" xlink:type="arc" use="optional" order="15" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems" xlink:to="loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract" xlink:title="Definition : loc_us-gaap_TemporaryEquityLineItems to loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract" xlink:type="arc" use="optional" order="16" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DerivativeLiabilitiesCurrent" xlink:label="loc_us-gaap_DerivativeLiabilitiesCurrent" xlink:title="DerivativeLiabilitiesCurrent" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems" xlink:to="loc_us-gaap_DerivativeLiabilitiesCurrent" xlink:title="Definition : loc_us-gaap_TemporaryEquityLineItems to loc_us-gaap_DerivativeLiabilitiesCurrent" xlink:type="arc" use="optional" order="17" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements" xlink:title="FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityLineItems" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements" xlink:title="Definition : loc_us-gaap_TemporaryEquityLineItems to loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements" xlink:type="arc" use="optional" order="19" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/DisclosureStockIncentivePlansDetails5">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:title="ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:title="ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems to loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis" xlink:title="AwardTypeAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:title="ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:title="Definition : loc_us-gaap_AwardTypeAxis to loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis" xlink:title="RangeAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember" xlink:title="RangeMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis" xlink:to="loc_us-gaap_RangeMember" xlink:title="Definition : loc_us-gaap_RangeAxis to loc_us-gaap_RangeMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_EmployeeStockOptionExcludingBonusCompensationMember" xlink:label="loc_vcyt_EmployeeStockOptionExcludingBonusCompensationMember" xlink:title="EmployeeStockOptionExcludingBonusCompensationMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_vcyt_EmployeeStockOptionExcludingBonusCompensationMember" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain to loc_vcyt_EmployeeStockOptionExcludingBonusCompensationMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember" xlink:title="MinimumMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember" xlink:to="loc_us-gaap_MinimumMember" xlink:title="Definition : loc_us-gaap_RangeMember to loc_us-gaap_MinimumMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract" xlink:title="ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum" xlink:title="ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract to loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum" xlink:type="arc" use="optional" order="1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="loc_us-gaap_AwardTypeAxis" xlink:title="Definition : loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable to loc_us-gaap_AwardTypeAxis" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_NonEmployeeStockOptionMember" xlink:label="loc_vcyt_NonEmployeeStockOptionMember" xlink:title="NonEmployeeStockOptionMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_vcyt_NonEmployeeStockOptionMember" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain to loc_vcyt_NonEmployeeStockOptionMember" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember" xlink:title="MaximumMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember" xlink:to="loc_us-gaap_MaximumMember" xlink:title="Definition : loc_us-gaap_RangeMember to loc_us-gaap_MaximumMember" xlink:type="arc" use="optional" order="2" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems to loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum" xlink:title="ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract to loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum" xlink:type="arc" use="optional" order="2" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="loc_us-gaap_RangeAxis" xlink:title="Definition : loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable to loc_us-gaap_RangeAxis" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_EmployeeStockOptionAnnualBonusCompensationMember" xlink:label="loc_vcyt_EmployeeStockOptionAnnualBonusCompensationMember" xlink:title="EmployeeStockOptionAnnualBonusCompensationMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_vcyt_EmployeeStockOptionAnnualBonusCompensationMember" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain to loc_vcyt_EmployeeStockOptionAnnualBonusCompensationMember" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:title="SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract to loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TitleOfIndividualAxis" xlink:label="loc_us-gaap_TitleOfIndividualAxis" xlink:title="TitleOfIndividualAxis" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="loc_us-gaap_TitleOfIndividualAxis" xlink:title="Definition : loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable to loc_us-gaap_TitleOfIndividualAxis" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum" xlink:title="ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract to loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum" xlink:type="arc" use="optional" order="4" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum" xlink:title="ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract to loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum" xlink:type="arc" use="optional" order="5" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:title="ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract to loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:type="arc" use="optional" order="6" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xlink:title="SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract to loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xlink:type="arc" use="optional" order="7" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:title="TitleOfIndividualWithRelationshipToEntityDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TitleOfIndividualAxis" xlink:to="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:title="Definition : loc_us-gaap_TitleOfIndividualAxis to loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_EmployeeStockOptionPerformanceBonusCompensationMember" xlink:label="loc_vcyt_EmployeeStockOptionPerformanceBonusCompensationMember" xlink:title="EmployeeStockOptionPerformanceBonusCompensationMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_vcyt_EmployeeStockOptionPerformanceBonusCompensationMember" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain to loc_vcyt_EmployeeStockOptionPerformanceBonusCompensationMember" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ChiefExecutiveOfficerMember" xlink:label="loc_us-gaap_ChiefExecutiveOfficerMember" xlink:title="ChiefExecutiveOfficerMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_us-gaap_ChiefExecutiveOfficerMember" xlink:title="Definition : loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain to loc_us-gaap_ChiefExecutiveOfficerMember" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:title="ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract to loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="TitleOfIndividualWithRelationshipToEntityDomain_1" xlink:title="TitleOfIndividualWithRelationshipToEntityDomain_1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TitleOfIndividualAxis" xlink:to="TitleOfIndividualWithRelationshipToEntityDomain_1" xlink:title="Definition : loc_us-gaap_TitleOfIndividualAxis to loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:type="arc" use="optional" order="8001" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:title="ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract to loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:type="arc" use="optional" order="8001" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/DisclosureOrganizationAndSummaryOfSignificantAccountingPoliciesDetails2">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems" xlink:title="PropertyPlantAndEquipmentLineItems" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:title="ScheduleOfPropertyPlantAndEquipmentTable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:title="Definition : loc_us-gaap_PropertyPlantAndEquipmentLineItems to loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis" xlink:title="RangeAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember" xlink:title="RangeMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis" xlink:to="loc_us-gaap_RangeMember" xlink:title="Definition : loc_us-gaap_RangeAxis to loc_us-gaap_RangeMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:title="PropertyPlantAndEquipmentByTypeAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:title="PropertyPlantAndEquipmentTypeDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:title="Definition : loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis to loc_us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember" xlink:title="MinimumMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember" xlink:to="loc_us-gaap_MinimumMember" xlink:title="Definition : loc_us-gaap_RangeMember to loc_us-gaap_MinimumMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SoftwareDevelopmentMember" xlink:label="loc_us-gaap_SoftwareDevelopmentMember" xlink:title="SoftwareDevelopmentMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="loc_us-gaap_SoftwareDevelopmentMember" xlink:title="Definition : loc_us-gaap_PropertyPlantAndEquipmentTypeDomain to loc_us-gaap_SoftwareDevelopmentMember" xlink:type="arc" use="optional" order="1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:title="Definition : loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable to loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="PropertyPlantAndEquipmentTypeDomain_1" xlink:title="PropertyPlantAndEquipmentTypeDomain_1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="PropertyPlantAndEquipmentTypeDomain_1" xlink:title="Definition : loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis to loc_us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember" xlink:title="MaximumMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember" xlink:to="loc_us-gaap_MaximumMember" xlink:title="Definition : loc_us-gaap_RangeMember to loc_us-gaap_MaximumMember" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:title="PropertyPlantAndEquipmentUsefulLife" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:title="Definition : loc_us-gaap_PropertyPlantAndEquipmentLineItems to loc_us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:type="arc" use="optional" order="2" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:to="loc_us-gaap_RangeAxis" xlink:title="Definition : loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable to loc_us-gaap_RangeAxis" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross" xlink:title="PropertyPlantAndEquipmentGross" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross" xlink:title="Definition : loc_us-gaap_PropertyPlantAndEquipmentLineItems to loc_us-gaap_PropertyPlantAndEquipmentGross" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:title="AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:title="Definition : loc_us-gaap_PropertyPlantAndEquipmentLineItems to loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:type="arc" use="optional" order="4" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet" xlink:title="PropertyPlantAndEquipmentNet" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet" xlink:title="Definition : loc_us-gaap_PropertyPlantAndEquipmentLineItems to loc_us-gaap_PropertyPlantAndEquipmentNet" xlink:type="arc" use="optional" order="5" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CapitalizedComputerSoftwareAdditions" xlink:label="loc_us-gaap_CapitalizedComputerSoftwareAdditions" xlink:title="CapitalizedComputerSoftwareAdditions" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="loc_us-gaap_CapitalizedComputerSoftwareAdditions" xlink:title="Definition : loc_us-gaap_PropertyPlantAndEquipmentLineItems to loc_us-gaap_CapitalizedComputerSoftwareAdditions" xlink:type="arc" use="optional" order="6" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CapitalizedComputerSoftwareAmortization" xlink:label="loc_us-gaap_CapitalizedComputerSoftwareAmortization" xlink:title="CapitalizedComputerSoftwareAmortization" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="loc_us-gaap_CapitalizedComputerSoftwareAmortization" xlink:title="Definition : loc_us-gaap_PropertyPlantAndEquipmentLineItems to loc_us-gaap_CapitalizedComputerSoftwareAmortization" xlink:type="arc" use="optional" order="7" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/DisclosureBalanceSheetComponentsDetails">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems" xlink:title="PropertyPlantAndEquipmentLineItems" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:title="ScheduleOfPropertyPlantAndEquipmentTable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:title="Definition : loc_us-gaap_PropertyPlantAndEquipmentLineItems to loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:title="PropertyPlantAndEquipmentByTypeAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:title="PropertyPlantAndEquipmentTypeDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:title="Definition : loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis to loc_us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis" xlink:title="IncomeStatementLocationAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain" xlink:title="IncomeStatementLocationDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis" xlink:to="loc_us-gaap_IncomeStatementLocationDomain" xlink:title="Definition : loc_us-gaap_IncomeStatementLocationAxis to loc_us-gaap_IncomeStatementLocationDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LeaseholdImprovementsMember" xlink:label="loc_us-gaap_LeaseholdImprovementsMember" xlink:title="LeaseholdImprovementsMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="loc_us-gaap_LeaseholdImprovementsMember" xlink:title="Definition : loc_us-gaap_PropertyPlantAndEquipmentTypeDomain to loc_us-gaap_LeaseholdImprovementsMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CostOfSalesMember" xlink:label="loc_us-gaap_CostOfSalesMember" xlink:title="CostOfSalesMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain" xlink:to="loc_us-gaap_CostOfSalesMember" xlink:title="Definition : loc_us-gaap_IncomeStatementLocationDomain to loc_us-gaap_CostOfSalesMember" xlink:type="arc" use="optional" order="1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:title="Definition : loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable to loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EquipmentMember" xlink:label="loc_us-gaap_EquipmentMember" xlink:title="EquipmentMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="loc_us-gaap_EquipmentMember" xlink:title="Definition : loc_us-gaap_PropertyPlantAndEquipmentTypeDomain to loc_us-gaap_EquipmentMember" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember" xlink:title="ResearchAndDevelopmentExpenseMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember" xlink:title="Definition : loc_us-gaap_IncomeStatementLocationDomain to loc_us-gaap_ResearchAndDevelopmentExpenseMember" xlink:type="arc" use="optional" order="2" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:to="loc_us-gaap_IncomeStatementLocationAxis" xlink:title="Definition : loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable to loc_us-gaap_IncomeStatementLocationAxis" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ComputerEquipmentMember" xlink:label="loc_us-gaap_ComputerEquipmentMember" xlink:title="ComputerEquipmentMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="loc_us-gaap_ComputerEquipmentMember" xlink:title="Definition : loc_us-gaap_PropertyPlantAndEquipmentTypeDomain to loc_us-gaap_ComputerEquipmentMember" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SellingAndMarketingExpenseMember" xlink:label="loc_us-gaap_SellingAndMarketingExpenseMember" xlink:title="SellingAndMarketingExpenseMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain" xlink:to="loc_us-gaap_SellingAndMarketingExpenseMember" xlink:title="Definition : loc_us-gaap_IncomeStatementLocationDomain to loc_us-gaap_SellingAndMarketingExpenseMember" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SoftwareAndSoftwareDevelopmentCostsMember" xlink:label="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember" xlink:title="SoftwareAndSoftwareDevelopmentCostsMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember" xlink:title="Definition : loc_us-gaap_PropertyPlantAndEquipmentTypeDomain to loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember" xlink:type="arc" use="optional" order="4" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_GeneralAndAdministrativeExpenseMember" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember" xlink:title="GeneralAndAdministrativeExpenseMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember" xlink:title="Definition : loc_us-gaap_IncomeStatementLocationDomain to loc_us-gaap_GeneralAndAdministrativeExpenseMember" xlink:type="arc" use="optional" order="4" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FurnitureAndFixturesMember" xlink:label="loc_us-gaap_FurnitureAndFixturesMember" xlink:title="FurnitureAndFixturesMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="loc_us-gaap_FurnitureAndFixturesMember" xlink:title="Definition : loc_us-gaap_PropertyPlantAndEquipmentTypeDomain to loc_us-gaap_FurnitureAndFixturesMember" xlink:type="arc" use="optional" order="5" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ConstructionInProgressMember" xlink:label="loc_us-gaap_ConstructionInProgressMember" xlink:title="ConstructionInProgressMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="loc_us-gaap_ConstructionInProgressMember" xlink:title="Definition : loc_us-gaap_PropertyPlantAndEquipmentTypeDomain to loc_us-gaap_ConstructionInProgressMember" xlink:type="arc" use="optional" order="6" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/DisclosureStockholdersEquityDetails">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfStockLineItems" xlink:label="loc_us-gaap_ClassOfStockLineItems" xlink:title="ClassOfStockLineItems" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfStockByClassTable" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable" xlink:title="ScheduleOfStockByClassTable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable" xlink:title="Definition : loc_us-gaap_ClassOfStockLineItems to loc_us-gaap_ScheduleOfStockByClassTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfWarrantOrRightAxis" xlink:label="loc_us-gaap_ClassOfWarrantOrRightAxis" xlink:title="ClassOfWarrantOrRightAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain" xlink:title="ClassOfWarrantOrRightDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain" xlink:title="Definition : loc_us-gaap_ClassOfWarrantOrRightAxis to loc_us-gaap_ClassOfWarrantOrRightDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis" xlink:title="AwardTypeAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:title="ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:title="Definition : loc_us-gaap_AwardTypeAxis to loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_CommonStockWarrantsMember" xlink:label="loc_vcyt_CommonStockWarrantsMember" xlink:title="CommonStockWarrantsMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain" xlink:to="loc_vcyt_CommonStockWarrantsMember" xlink:title="Definition : loc_us-gaap_ClassOfWarrantOrRightDomain to loc_vcyt_CommonStockWarrantsMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_EmployeeAndNonEmployeeStockOptionMember" xlink:label="loc_vcyt_EmployeeAndNonEmployeeStockOptionMember" xlink:title="EmployeeAndNonEmployeeStockOptionMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_vcyt_EmployeeAndNonEmployeeStockOptionMember" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain to loc_vcyt_EmployeeAndNonEmployeeStockOptionMember" xlink:type="arc" use="optional" order="1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable" xlink:to="loc_us-gaap_ClassOfWarrantOrRightAxis" xlink:title="Definition : loc_us-gaap_ScheduleOfStockByClassTable to loc_us-gaap_ClassOfWarrantOrRightAxis" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:title="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:title="Definition : loc_us-gaap_ClassOfStockLineItems to loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:type="arc" use="optional" order="2" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable" xlink:to="loc_us-gaap_AwardTypeAxis" xlink:title="Definition : loc_us-gaap_ScheduleOfStockByClassTable to loc_us-gaap_AwardTypeAxis" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:title="ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:title="Definition : loc_us-gaap_ClassOfStockLineItems to loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis" xlink:title="StatementClassOfStockAxis" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable" xlink:to="loc_us-gaap_StatementClassOfStockAxis" xlink:title="Definition : loc_us-gaap_ScheduleOfStockByClassTable to loc_us-gaap_StatementClassOfStockAxis" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" xlink:label="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" xlink:title="ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems" xlink:to="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" xlink:title="Definition : loc_us-gaap_ClassOfStockLineItems to loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" xlink:type="arc" use="optional" order="4" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" xlink:label="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" xlink:title="CommonStockCapitalSharesReservedForFutureIssuance" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems" xlink:to="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" xlink:title="Definition : loc_us-gaap_ClassOfStockLineItems to loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance" xlink:type="arc" use="optional" order="5" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PreferredStockSharesAuthorized" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized" xlink:title="PreferredStockSharesAuthorized" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized" xlink:title="Definition : loc_us-gaap_ClassOfStockLineItems to loc_us-gaap_PreferredStockSharesAuthorized" xlink:type="arc" use="optional" order="6" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PreferredStockParOrStatedValuePerShare" xlink:label="loc_us-gaap_PreferredStockParOrStatedValuePerShare" xlink:title="PreferredStockParOrStatedValuePerShare" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems" xlink:to="loc_us-gaap_PreferredStockParOrStatedValuePerShare" xlink:title="Definition : loc_us-gaap_ClassOfStockLineItems to loc_us-gaap_PreferredStockParOrStatedValuePerShare" xlink:type="arc" use="optional" order="7" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PreferredStockSharesIssued" xlink:label="loc_us-gaap_PreferredStockSharesIssued" xlink:title="PreferredStockSharesIssued" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems" xlink:to="loc_us-gaap_PreferredStockSharesIssued" xlink:title="Definition : loc_us-gaap_ClassOfStockLineItems to loc_us-gaap_PreferredStockSharesIssued" xlink:type="arc" use="optional" order="8" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PreferredStockSharesOutstanding" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding" xlink:title="PreferredStockSharesOutstanding" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems" xlink:to="loc_us-gaap_PreferredStockSharesOutstanding" xlink:title="Definition : loc_us-gaap_ClassOfStockLineItems to loc_us-gaap_PreferredStockSharesOutstanding" xlink:type="arc" use="optional" order="9" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain" xlink:title="ClassOfStockDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis" xlink:to="loc_us-gaap_ClassOfStockDomain" xlink:title="Definition : loc_us-gaap_StatementClassOfStockAxis to loc_us-gaap_ClassOfStockDomain" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_SeriesAConvertiblePreferredStockMember" xlink:label="loc_vcyt_SeriesAConvertiblePreferredStockMember" xlink:title="SeriesAConvertiblePreferredStockMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain" xlink:to="loc_vcyt_SeriesAConvertiblePreferredStockMember" xlink:title="Definition : loc_us-gaap_ClassOfStockDomain to loc_vcyt_SeriesAConvertiblePreferredStockMember" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ConversionOfStockSharesIssuedAsIfConverted" xlink:label="loc_vcyt_ConversionOfStockSharesIssuedAsIfConverted" xlink:title="ConversionOfStockSharesIssuedAsIfConverted" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems" xlink:to="loc_vcyt_ConversionOfStockSharesIssuedAsIfConverted" xlink:title="Definition : loc_us-gaap_ClassOfStockLineItems to loc_vcyt_ConversionOfStockSharesIssuedAsIfConverted" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_SeriesBConvertiblePreferredStockMember" xlink:label="loc_vcyt_SeriesBConvertiblePreferredStockMember" xlink:title="SeriesBConvertiblePreferredStockMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain" xlink:to="loc_vcyt_SeriesBConvertiblePreferredStockMember" xlink:title="Definition : loc_us-gaap_ClassOfStockDomain to loc_vcyt_SeriesBConvertiblePreferredStockMember" xlink:type="arc" use="optional" order="8001" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ConversionOfStockSharesIssuedAsIfConvertedConvertiblePreferredStockReservedForIssuance" xlink:label="loc_vcyt_ConversionOfStockSharesIssuedAsIfConvertedConvertiblePreferredStockReservedForIssuance" xlink:title="ConversionOfStockSharesIssuedAsIfConvertedConvertiblePreferredStockReservedForIssuance" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems" xlink:to="loc_vcyt_ConversionOfStockSharesIssuedAsIfConvertedConvertiblePreferredStockReservedForIssuance" xlink:title="Definition : loc_us-gaap_ClassOfStockLineItems to loc_vcyt_ConversionOfStockSharesIssuedAsIfConvertedConvertiblePreferredStockReservedForIssuance" xlink:type="arc" use="optional" order="8001" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_SeriesCConvertiblePreferredStockMember" xlink:label="loc_vcyt_SeriesCConvertiblePreferredStockMember" xlink:title="SeriesCConvertiblePreferredStockMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain" xlink:to="loc_vcyt_SeriesCConvertiblePreferredStockMember" xlink:title="Definition : loc_us-gaap_ClassOfStockDomain to loc_vcyt_SeriesCConvertiblePreferredStockMember" xlink:type="arc" use="optional" order="8002" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/DisclosureIncomeTaxesDetails">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OperatingLossCarryforwardsLineItems" xlink:label="loc_us-gaap_OperatingLossCarryforwardsLineItems" xlink:title="OperatingLossCarryforwardsLineItems" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OperatingLossCarryforwardsTable" xlink:label="loc_us-gaap_OperatingLossCarryforwardsTable" xlink:title="OperatingLossCarryforwardsTable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems" xlink:to="loc_us-gaap_OperatingLossCarryforwardsTable" xlink:title="Definition : loc_us-gaap_OperatingLossCarryforwardsLineItems to loc_us-gaap_OperatingLossCarryforwardsTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis" xlink:title="IncomeTaxAuthorityAxis" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis" xlink:title="Definition : loc_us-gaap_OperatingLossCarryforwardsTable to loc_us-gaap_IncomeTaxAuthorityAxis" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain" xlink:title="IncomeTaxAuthorityDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain" xlink:title="Definition : loc_us-gaap_IncomeTaxAuthorityAxis to loc_us-gaap_IncomeTaxAuthorityDomain" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_InternalRevenueServiceIRSMember" xlink:label="loc_us-gaap_InternalRevenueServiceIRSMember" xlink:title="InternalRevenueServiceIRSMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain" xlink:to="loc_us-gaap_InternalRevenueServiceIRSMember" xlink:title="Definition : loc_us-gaap_IncomeTaxAuthorityDomain to loc_us-gaap_InternalRevenueServiceIRSMember" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OperatingLossCarryforwards" xlink:label="loc_us-gaap_OperatingLossCarryforwards" xlink:title="OperatingLossCarryforwards" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems" xlink:to="loc_us-gaap_OperatingLossCarryforwards" xlink:title="Definition : loc_us-gaap_OperatingLossCarryforwardsLineItems to loc_us-gaap_OperatingLossCarryforwards" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="IncomeTaxAuthorityDomain_1" xlink:title="IncomeTaxAuthorityDomain_1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis" xlink:to="IncomeTaxAuthorityDomain_1" xlink:title="Definition : loc_us-gaap_IncomeTaxAuthorityAxis to loc_us-gaap_IncomeTaxAuthorityDomain" xlink:type="arc" use="optional" order="8001" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StateAndLocalJurisdictionMember" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember" xlink:title="StateAndLocalJurisdictionMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember" xlink:title="Definition : loc_us-gaap_IncomeTaxAuthorityDomain to loc_us-gaap_StateAndLocalJurisdictionMember" xlink:type="arc" use="optional" order="8001" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/DisclosureIncomeTaxesDetails2">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TaxCreditCarryforwardLineItems" xlink:label="loc_us-gaap_TaxCreditCarryforwardLineItems" xlink:title="TaxCreditCarryforwardLineItems" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TaxCreditCarryforwardTable" xlink:label="loc_us-gaap_TaxCreditCarryforwardTable" xlink:title="TaxCreditCarryforwardTable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems" xlink:to="loc_us-gaap_TaxCreditCarryforwardTable" xlink:title="Definition : loc_us-gaap_TaxCreditCarryforwardLineItems to loc_us-gaap_TaxCreditCarryforwardTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis" xlink:title="IncomeTaxAuthorityAxis" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_TaxCreditCarryforwardTable" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis" xlink:title="Definition : loc_us-gaap_TaxCreditCarryforwardTable to loc_us-gaap_IncomeTaxAuthorityAxis" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain" xlink:title="IncomeTaxAuthorityDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain" xlink:title="Definition : loc_us-gaap_IncomeTaxAuthorityAxis to loc_us-gaap_IncomeTaxAuthorityDomain" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_InternalRevenueServiceIRSMember" xlink:label="loc_us-gaap_InternalRevenueServiceIRSMember" xlink:title="InternalRevenueServiceIRSMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain" xlink:to="loc_us-gaap_InternalRevenueServiceIRSMember" xlink:title="Definition : loc_us-gaap_IncomeTaxAuthorityDomain to loc_us-gaap_InternalRevenueServiceIRSMember" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TaxCreditCarryforwardAmount" xlink:label="loc_us-gaap_TaxCreditCarryforwardAmount" xlink:title="TaxCreditCarryforwardAmount" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems" xlink:to="loc_us-gaap_TaxCreditCarryforwardAmount" xlink:title="Definition : loc_us-gaap_TaxCreditCarryforwardLineItems to loc_us-gaap_TaxCreditCarryforwardAmount" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward" xlink:label="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward" xlink:title="ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions" xlink:title="UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions" xlink:title="Definition : loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward to loc_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StateAndLocalJurisdictionMember" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember" xlink:title="StateAndLocalJurisdictionMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember" xlink:title="Definition : loc_us-gaap_IncomeTaxAuthorityDomain to loc_us-gaap_StateAndLocalJurisdictionMember" xlink:type="arc" use="optional" order="8001" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations" xlink:title="UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations" xlink:title="Definition : loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward to loc_us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations" xlink:type="arc" use="optional" order="8001" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems" xlink:to="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward" xlink:title="Definition : loc_us-gaap_TaxCreditCarryforwardLineItems to loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward" xlink:type="arc" use="optional" order="8002" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions" xlink:title="UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions" xlink:title="Definition : loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward to loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions" xlink:type="arc" use="optional" order="8002" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions" xlink:title="UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions" xlink:title="Definition : loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward to loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions" xlink:type="arc" use="optional" order="8003" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense" xlink:title="UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardLineItems" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense" xlink:title="Definition : loc_us-gaap_TaxCreditCarryforwardLineItems to loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense" xlink:type="arc" use="optional" order="8003" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/DisclosureIncomeTaxesDetails3">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxExaminationLineItems" xlink:label="loc_us-gaap_IncomeTaxExaminationLineItems" xlink:title="IncomeTaxExaminationLineItems" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxExaminationTable" xlink:label="loc_us-gaap_IncomeTaxExaminationTable" xlink:title="IncomeTaxExaminationTable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems" xlink:to="loc_us-gaap_IncomeTaxExaminationTable" xlink:title="Definition : loc_us-gaap_IncomeTaxExaminationLineItems to loc_us-gaap_IncomeTaxExaminationTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis" xlink:title="IncomeTaxAuthorityAxis" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxExaminationTable" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis" xlink:title="Definition : loc_us-gaap_IncomeTaxExaminationTable to loc_us-gaap_IncomeTaxAuthorityAxis" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain" xlink:title="IncomeTaxAuthorityDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain" xlink:title="Definition : loc_us-gaap_IncomeTaxAuthorityAxis to loc_us-gaap_IncomeTaxAuthorityDomain" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_InternalRevenueServiceIRSMember" xlink:label="loc_us-gaap_InternalRevenueServiceIRSMember" xlink:title="InternalRevenueServiceIRSMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain" xlink:to="loc_us-gaap_InternalRevenueServiceIRSMember" xlink:title="Definition : loc_us-gaap_IncomeTaxAuthorityDomain to loc_us-gaap_InternalRevenueServiceIRSMember" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_IncomeTaxExaminationPeriod" xlink:label="loc_vcyt_IncomeTaxExaminationPeriod" xlink:title="IncomeTaxExaminationPeriod" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems" xlink:to="loc_vcyt_IncomeTaxExaminationPeriod" xlink:title="Definition : loc_us-gaap_IncomeTaxExaminationLineItems to loc_vcyt_IncomeTaxExaminationPeriod" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StateAndLocalJurisdictionMember" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember" xlink:title="StateAndLocalJurisdictionMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember" xlink:title="Definition : loc_us-gaap_IncomeTaxAuthorityDomain to loc_us-gaap_StateAndLocalJurisdictionMember" xlink:type="arc" use="optional" order="8001" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/DisclosureSubsequentEventsDetails">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SubsequentEventLineItems" xlink:label="loc_us-gaap_SubsequentEventLineItems" xlink:title="SubsequentEventLineItems" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SubsequentEventTable" xlink:label="loc_us-gaap_SubsequentEventTable" xlink:title="SubsequentEventTable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems" xlink:to="loc_us-gaap_SubsequentEventTable" xlink:title="Definition : loc_us-gaap_SubsequentEventLineItems to loc_us-gaap_SubsequentEventTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis" xlink:title="RangeAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember" xlink:title="RangeMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis" xlink:to="loc_us-gaap_RangeMember" xlink:title="Definition : loc_us-gaap_RangeAxis to loc_us-gaap_RangeMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis" xlink:title="SubsequentEventTypeAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain" xlink:title="SubsequentEventTypeDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis" xlink:to="loc_us-gaap_SubsequentEventTypeDomain" xlink:title="Definition : loc_us-gaap_SubsequentEventTypeAxis to loc_us-gaap_SubsequentEventTypeDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember" xlink:title="MaximumMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember" xlink:to="loc_us-gaap_MaximumMember" xlink:title="Definition : loc_us-gaap_RangeMember to loc_us-gaap_MaximumMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaap_SubsequentEventMember" xlink:title="SubsequentEventMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain" xlink:to="loc_us-gaap_SubsequentEventMember" xlink:title="Definition : loc_us-gaap_SubsequentEventTypeDomain to loc_us-gaap_SubsequentEventMember" xlink:type="arc" use="optional" order="1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable" xlink:to="loc_us-gaap_SubsequentEventTypeAxis" xlink:title="Definition : loc_us-gaap_SubsequentEventTable to loc_us-gaap_SubsequentEventTypeAxis" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="SubsequentEventTypeDomain_1" xlink:title="SubsequentEventTypeDomain_1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis" xlink:to="SubsequentEventTypeDomain_1" xlink:title="Definition : loc_us-gaap_SubsequentEventTypeAxis to loc_us-gaap_SubsequentEventTypeDomain" xlink:type="arc" use="optional" order="2" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable" xlink:to="loc_us-gaap_RangeAxis" xlink:title="Definition : loc_us-gaap_SubsequentEventTable to loc_us-gaap_RangeAxis" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ClassOfWarrantOrRightNumberOfSharesOfPreferredStockWarrantsConverted" xlink:label="loc_vcyt_ClassOfWarrantOrRightNumberOfSharesOfPreferredStockWarrantsConverted" xlink:title="ClassOfWarrantOrRightNumberOfSharesOfPreferredStockWarrantsConverted" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems" xlink:to="loc_vcyt_ClassOfWarrantOrRightNumberOfSharesOfPreferredStockWarrantsConverted" xlink:title="Definition : loc_us-gaap_SubsequentEventLineItems to loc_vcyt_ClassOfWarrantOrRightNumberOfSharesOfPreferredStockWarrantsConverted" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ClassOfWarrantOrRightSharesOfCommonStockWarrantsIssuedUponConversionOfSharesOfPreferredStockWarrants" xlink:label="loc_vcyt_ClassOfWarrantOrRightSharesOfCommonStockWarrantsIssuedUponConversionOfSharesOfPreferredStockWarrants" xlink:title="ClassOfWarrantOrRightSharesOfCommonStockWarrantsIssuedUponConversionOfSharesOfPreferredStockWarrants" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems" xlink:to="loc_vcyt_ClassOfWarrantOrRightSharesOfCommonStockWarrantsIssuedUponConversionOfSharesOfPreferredStockWarrants" xlink:title="Definition : loc_us-gaap_SubsequentEventLineItems to loc_vcyt_ClassOfWarrantOrRightSharesOfCommonStockWarrantsIssuedUponConversionOfSharesOfPreferredStockWarrants" xlink:type="arc" use="optional" order="4" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_PreferredStockNumberOfSeries" xlink:label="loc_vcyt_PreferredStockNumberOfSeries" xlink:title="PreferredStockNumberOfSeries" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems" xlink:to="loc_vcyt_PreferredStockNumberOfSeries" xlink:title="Definition : loc_us-gaap_SubsequentEventLineItems to loc_vcyt_PreferredStockNumberOfSeries" xlink:type="arc" use="optional" order="5" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/DisclosureSummaryOfSignificantAccountingPoliciesDetails4">
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_OrganizationAndSummaryOfSignificantAccountingPoliciesLineItems" xlink:label="loc_vcyt_OrganizationAndSummaryOfSignificantAccountingPoliciesLineItems" xlink:title="OrganizationAndSummaryOfSignificantAccountingPoliciesLineItems" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_OrganizationAndSummaryOfSignificantAccountingPoliciesTable" xlink:label="loc_vcyt_OrganizationAndSummaryOfSignificantAccountingPoliciesTable" xlink:title="OrganizationAndSummaryOfSignificantAccountingPoliciesTable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_vcyt_OrganizationAndSummaryOfSignificantAccountingPoliciesLineItems" xlink:to="loc_vcyt_OrganizationAndSummaryOfSignificantAccountingPoliciesTable" xlink:title="Definition : loc_vcyt_OrganizationAndSummaryOfSignificantAccountingPoliciesLineItems to loc_vcyt_OrganizationAndSummaryOfSignificantAccountingPoliciesTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis" xlink:title="SubsequentEventTypeAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain" xlink:title="SubsequentEventTypeDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis" xlink:to="loc_us-gaap_SubsequentEventTypeDomain" xlink:title="Definition : loc_us-gaap_SubsequentEventTypeAxis to loc_us-gaap_SubsequentEventTypeDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaap_SubsequentEventMember" xlink:title="SubsequentEventMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain" xlink:to="loc_us-gaap_SubsequentEventMember" xlink:title="Definition : loc_us-gaap_SubsequentEventTypeDomain to loc_us-gaap_SubsequentEventMember" xlink:type="arc" use="optional" order="1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_vcyt_OrganizationAndSummaryOfSignificantAccountingPoliciesTable" xlink:to="loc_us-gaap_SubsequentEventTypeAxis" xlink:title="Definition : loc_vcyt_OrganizationAndSummaryOfSignificantAccountingPoliciesTable to loc_us-gaap_SubsequentEventTypeAxis" xlink:type="arc" use="optional" order="1" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/DisclosureStockIncentivePlansDetails4">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:title="EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:title="ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:to="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:title="Definition : loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems to loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis" xlink:title="AwardTypeAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:title="ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:title="Definition : loc_us-gaap_AwardTypeAxis to loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis" xlink:title="IncomeStatementLocationAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain" xlink:title="IncomeStatementLocationDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis" xlink:to="loc_us-gaap_IncomeStatementLocationDomain" xlink:title="Definition : loc_us-gaap_IncomeStatementLocationAxis to loc_us-gaap_IncomeStatementLocationDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_EmployeeAndNonEmployeeStockOptionExcludingBonusCompensationMember" xlink:label="loc_vcyt_EmployeeAndNonEmployeeStockOptionExcludingBonusCompensationMember" xlink:title="EmployeeAndNonEmployeeStockOptionExcludingBonusCompensationMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_vcyt_EmployeeAndNonEmployeeStockOptionExcludingBonusCompensationMember" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain to loc_vcyt_EmployeeAndNonEmployeeStockOptionExcludingBonusCompensationMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CostOfSalesMember" xlink:label="loc_us-gaap_CostOfSalesMember" xlink:title="CostOfSalesMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain" xlink:to="loc_us-gaap_CostOfSalesMember" xlink:title="Definition : loc_us-gaap_IncomeStatementLocationDomain to loc_us-gaap_CostOfSalesMember" xlink:type="arc" use="optional" order="1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:to="loc_us-gaap_AwardTypeAxis" xlink:title="Definition : loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable to loc_us-gaap_AwardTypeAxis" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="IncomeStatementLocationDomain_1" xlink:title="IncomeStatementLocationDomain_1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis" xlink:to="IncomeStatementLocationDomain_1" xlink:title="Definition : loc_us-gaap_IncomeStatementLocationAxis to loc_us-gaap_IncomeStatementLocationDomain" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember" xlink:title="ResearchAndDevelopmentExpenseMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember" xlink:title="Definition : loc_us-gaap_IncomeStatementLocationDomain to loc_us-gaap_ResearchAndDevelopmentExpenseMember" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense" xlink:title="AllocatedShareBasedCompensationExpense" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense" xlink:title="Definition : loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems to loc_us-gaap_AllocatedShareBasedCompensationExpense" xlink:type="arc" use="optional" order="2" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:to="loc_us-gaap_IncomeStatementLocationAxis" xlink:title="Definition : loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable to loc_us-gaap_IncomeStatementLocationAxis" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SellingAndMarketingExpenseMember" xlink:label="loc_us-gaap_SellingAndMarketingExpenseMember" xlink:title="SellingAndMarketingExpenseMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain" xlink:to="loc_us-gaap_SellingAndMarketingExpenseMember" xlink:title="Definition : loc_us-gaap_IncomeStatementLocationDomain to loc_us-gaap_SellingAndMarketingExpenseMember" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions" xlink:title="EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions" xlink:title="Definition : loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems to loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_GeneralAndAdministrativeExpenseMember" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember" xlink:title="GeneralAndAdministrativeExpenseMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember" xlink:title="Definition : loc_us-gaap_IncomeStatementLocationDomain to loc_us-gaap_GeneralAndAdministrativeExpenseMember" xlink:type="arc" use="optional" order="4" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:title="EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:title="Definition : loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems to loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:type="arc" use="optional" order="4" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_EmployeeStockOptionBonusCompensationMember" xlink:label="loc_vcyt_EmployeeStockOptionBonusCompensationMember" xlink:title="EmployeeStockOptionBonusCompensationMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_vcyt_EmployeeStockOptionBonusCompensationMember" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain to loc_vcyt_EmployeeStockOptionBonusCompensationMember" xlink:type="arc" use="optional" order="8000" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/DisclosureStockIncentivePlanDetails7">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:title="ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:title="ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems to loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis" xlink:title="AwardTypeAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:title="ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:title="Definition : loc_us-gaap_AwardTypeAxis to loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis" xlink:title="RangeAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember" xlink:title="RangeMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis" xlink:to="loc_us-gaap_RangeMember" xlink:title="Definition : loc_us-gaap_RangeAxis to loc_us-gaap_RangeMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TitleOfIndividualAxis" xlink:label="loc_us-gaap_TitleOfIndividualAxis" xlink:title="TitleOfIndividualAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:title="TitleOfIndividualWithRelationshipToEntityDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TitleOfIndividualAxis" xlink:to="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:title="Definition : loc_us-gaap_TitleOfIndividualAxis to loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PlanNameAxis" xlink:label="loc_us-gaap_PlanNameAxis" xlink:title="PlanNameAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain" xlink:title="PlanNameDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis" xlink:to="loc_us-gaap_PlanNameDomain" xlink:title="Definition : loc_us-gaap_PlanNameAxis to loc_us-gaap_PlanNameDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_EmployeeAndNonEmployeeStockOptionMember" xlink:label="loc_vcyt_EmployeeAndNonEmployeeStockOptionMember" xlink:title="EmployeeAndNonEmployeeStockOptionMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_vcyt_EmployeeAndNonEmployeeStockOptionMember" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain to loc_vcyt_EmployeeAndNonEmployeeStockOptionMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_IncentiveStockOptionsMember" xlink:label="loc_vcyt_IncentiveStockOptionsMember" xlink:title="IncentiveStockOptionsMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_vcyt_EmployeeAndNonEmployeeStockOptionMember" xlink:to="loc_vcyt_IncentiveStockOptionsMember" xlink:title="Definition : loc_vcyt_EmployeeAndNonEmployeeStockOptionMember to loc_vcyt_IncentiveStockOptionsMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember" xlink:title="MinimumMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember" xlink:to="loc_us-gaap_MinimumMember" xlink:title="Definition : loc_us-gaap_RangeMember to loc_us-gaap_MinimumMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_EmployeeNewlyHiredMember" xlink:label="loc_vcyt_EmployeeNewlyHiredMember" xlink:title="EmployeeNewlyHiredMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_vcyt_EmployeeNewlyHiredMember" xlink:title="Definition : loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain to loc_vcyt_EmployeeNewlyHiredMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_StockPlan2008Member" xlink:label="loc_vcyt_StockPlan2008Member" xlink:title="StockPlan2008Member" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain" xlink:to="loc_vcyt_StockPlan2008Member" xlink:title="Definition : loc_us-gaap_PlanNameDomain to loc_vcyt_StockPlan2008Member" xlink:type="arc" use="optional" order="1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="loc_us-gaap_PlanNameAxis" xlink:title="Definition : loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable to loc_us-gaap_PlanNameAxis" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1" xlink:title="ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis" xlink:to="ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1" xlink:title="Definition : loc_us-gaap_AwardTypeAxis to loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeMember" xlink:label="RangeMember_2" xlink:title="RangeMember_2" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis" xlink:to="RangeMember_2" xlink:title="Definition : loc_us-gaap_RangeAxis to loc_us-gaap_RangeMember" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="PlanNameDomain_3" xlink:title="PlanNameDomain_3" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis" xlink:to="PlanNameDomain_3" xlink:title="Definition : loc_us-gaap_PlanNameAxis to loc_us-gaap_PlanNameDomain" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_NonStatutoryStockOptionsMember" xlink:label="loc_vcyt_NonStatutoryStockOptionsMember" xlink:title="NonStatutoryStockOptionsMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_vcyt_EmployeeAndNonEmployeeStockOptionMember" xlink:to="loc_vcyt_NonStatutoryStockOptionsMember" xlink:title="Definition : loc_vcyt_EmployeeAndNonEmployeeStockOptionMember to loc_vcyt_NonStatutoryStockOptionsMember" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember" xlink:title="MaximumMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember" xlink:to="loc_us-gaap_MaximumMember" xlink:title="Definition : loc_us-gaap_RangeMember to loc_us-gaap_MaximumMember" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_OutsideDirectorWhoWasNotPreviouslyEmployeeMember" xlink:label="loc_vcyt_OutsideDirectorWhoWasNotPreviouslyEmployeeMember" xlink:title="OutsideDirectorWhoWasNotPreviouslyEmployeeMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_vcyt_OutsideDirectorWhoWasNotPreviouslyEmployeeMember" xlink:title="Definition : loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain to loc_vcyt_OutsideDirectorWhoWasNotPreviouslyEmployeeMember" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_StockIncentivePlan2013Member" xlink:label="loc_vcyt_StockIncentivePlan2013Member" xlink:title="StockIncentivePlan2013Member" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain" xlink:to="loc_vcyt_StockIncentivePlan2013Member" xlink:title="Definition : loc_us-gaap_PlanNameDomain to loc_vcyt_StockIncentivePlan2013Member" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" xlink:title="SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems to loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" xlink:type="arc" use="optional" order="2" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="loc_us-gaap_AwardTypeAxis" xlink:title="Definition : loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable to loc_us-gaap_AwardTypeAxis" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_OutsideDirectorServingAsMemberOfBoardOfDirectorsForAtLeastSixMonthsMember" xlink:label="loc_vcyt_OutsideDirectorServingAsMemberOfBoardOfDirectorsForAtLeastSixMonthsMember" xlink:title="OutsideDirectorServingAsMemberOfBoardOfDirectorsForAtLeastSixMonthsMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_vcyt_OutsideDirectorServingAsMemberOfBoardOfDirectorsForAtLeastSixMonthsMember" xlink:title="Definition : loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain to loc_vcyt_OutsideDirectorServingAsMemberOfBoardOfDirectorsForAtLeastSixMonthsMember" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfVotingPowerOfAllClassesOfStock" xlink:label="loc_vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfVotingPowerOfAllClassesOfStock" xlink:title="ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfVotingPowerOfAllClassesOfStock" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfVotingPowerOfAllClassesOfStock" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems to loc_vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfVotingPowerOfAllClassesOfStock" xlink:type="arc" use="optional" order="3" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="loc_us-gaap_TitleOfIndividualAxis" xlink:title="Definition : loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable to loc_us-gaap_TitleOfIndividualAxis" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_OutsideDirectorMember" xlink:label="loc_vcyt_OutsideDirectorMember" xlink:title="OutsideDirectorMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_vcyt_OutsideDirectorMember" xlink:title="Definition : loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain to loc_vcyt_OutsideDirectorMember" xlink:type="arc" use="optional" order="4" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardTermOfOptionsGrantedToEmployeesWhoOwnedSpecifiedPercentageOfClassOfStock" xlink:label="loc_vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardTermOfOptionsGrantedToEmployeesWhoOwnedSpecifiedPercentageOfClassOfStock" xlink:title="ShareBasedCompensationArrangementByShareBasedPaymentAwardTermOfOptionsGrantedToEmployeesWhoOwnedSpecifiedPercentageOfClassOfStock" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardTermOfOptionsGrantedToEmployeesWhoOwnedSpecifiedPercentageOfClassOfStock" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems to loc_vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardTermOfOptionsGrantedToEmployeesWhoOwnedSpecifiedPercentageOfClassOfStock" xlink:type="arc" use="optional" order="4" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="loc_us-gaap_RangeAxis" xlink:title="Definition : loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable to loc_us-gaap_RangeAxis" xlink:type="arc" use="optional" order="4" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent" xlink:title="SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems to loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent" xlink:type="arc" use="optional" order="5" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfStockPercentageForGrantsToPersonsWhoOwnedSpecifiedPercentageOfClassOfStock" xlink:label="loc_vcyt_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfStockPercentageForGrantsToPersonsWhoOwnedSpecifiedPercentageOfClassOfStock" xlink:title="SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfStockPercentageForGrantsToPersonsWhoOwnedSpecifiedPercentageOfClassOfStock" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_vcyt_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfStockPercentageForGrantsToPersonsWhoOwnedSpecifiedPercentageOfClassOfStock" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems to loc_vcyt_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfStockPercentageForGrantsToPersonsWhoOwnedSpecifiedPercentageOfClassOfStock" xlink:type="arc" use="optional" order="6" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:title="ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems to loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:type="arc" use="optional" order="7" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentageYearOne" xlink:label="loc_vcyt_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentageYearOne" xlink:title="SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentageYearOne" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_vcyt_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentageYearOne" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems to loc_vcyt_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentageYearOne" xlink:type="arc" use="optional" order="8" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_CommonStockCapitalAdditionalSharesReservedForFutureIssuance" xlink:label="loc_vcyt_CommonStockCapitalAdditionalSharesReservedForFutureIssuance" xlink:title="CommonStockCapitalAdditionalSharesReservedForFutureIssuance" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_vcyt_CommonStockCapitalAdditionalSharesReservedForFutureIssuance" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems to loc_vcyt_CommonStockCapitalAdditionalSharesReservedForFutureIssuance" xlink:type="arc" use="optional" order="9" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum" xlink:title="ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems to loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum" xlink:type="arc" use="optional" order="10" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAnnualGrants" xlink:label="loc_vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAnnualGrants" xlink:title="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAnnualGrants" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAnnualGrants" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems to loc_vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAnnualGrants" xlink:type="arc" use="optional" order="11" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsInitialGrants" xlink:label="loc_vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsInitialGrants" xlink:title="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsInitialGrants" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsInitialGrants" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems to loc_vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsInitialGrants" xlink:type="arc" use="optional" order="12" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageVestingOnMonthlyBasis" xlink:label="loc_vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageVestingOnMonthlyBasis" xlink:title="ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageVestingOnMonthlyBasis" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageVestingOnMonthlyBasis" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems to loc_vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageVestingOnMonthlyBasis" xlink:type="arc" use="optional" order="13" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPeriodOverWhichVestingWillBeOnMonthlyBasis" xlink:label="loc_vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPeriodOverWhichVestingWillBeOnMonthlyBasis" xlink:title="ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPeriodOverWhichVestingWillBeOnMonthlyBasis" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPeriodOverWhichVestingWillBeOnMonthlyBasis" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems to loc_vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPeriodOverWhichVestingWillBeOnMonthlyBasis" xlink:type="arc" use="optional" order="14" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardPeriodForWhichDirectorHasToServeAsBoardOfDirectorToReceiveGrantToPurchaseShares" xlink:label="loc_vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardPeriodForWhichDirectorHasToServeAsBoardOfDirectorToReceiveGrantToPurchaseShares" xlink:title="ShareBasedCompensationArrangementByShareBasedPaymentAwardPeriodForWhichDirectorHasToServeAsBoardOfDirectorToReceiveGrantToPurchaseShares" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardPeriodForWhichDirectorHasToServeAsBoardOfDirectorToReceiveGrantToPurchaseShares" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems to loc_vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardPeriodForWhichDirectorHasToServeAsBoardOfDirectorToReceiveGrantToPurchaseShares" xlink:type="arc" use="optional" order="15" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardExpirationPeriodAfterTermination" xlink:label="loc_vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardExpirationPeriodAfterTermination" xlink:title="ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardExpirationPeriodAfterTermination" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardExpirationPeriodAfterTermination" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems to loc_vcyt_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardExpirationPeriodAfterTermination" xlink:type="arc" use="optional" order="16" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember" xlink:title="EmployeeStockOptionMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaap_EmployeeStockOptionMember" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain to loc_us-gaap_EmployeeStockOptionMember" xlink:type="arc" use="optional" order="8000" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/DisclosureGenzymeCopromotionAgreementDetails">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:label="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:title="CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:label="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:title="ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:title="Definition : loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems to loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis" xlink:title="RangeAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember" xlink:title="RangeMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis" xlink:to="loc_us-gaap_RangeMember" xlink:title="Definition : loc_us-gaap_RangeAxis to loc_us-gaap_RangeMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="loc_us-gaap_TypeOfArrangementAxis" xlink:title="TypeOfArrangementAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:title="ArrangementsAndNonarrangementTransactionsMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TypeOfArrangementAxis" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:title="Definition : loc_us-gaap_TypeOfArrangementAxis to loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis" xlink:title="LegalEntityAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain" xlink:title="EntityDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis" xlink:to="loc_dei_EntityDomain" xlink:title="Definition : loc_dei_LegalEntityAxis to loc_dei_EntityDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember" xlink:title="MaximumMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember" xlink:to="loc_us-gaap_MaximumMember" xlink:title="Definition : loc_us-gaap_RangeMember to loc_us-gaap_MaximumMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CollaborativeArrangementCopromotionMember" xlink:label="loc_us-gaap_CollaborativeArrangementCopromotionMember" xlink:title="CollaborativeArrangementCopromotionMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_us-gaap_CollaborativeArrangementCopromotionMember" xlink:title="Definition : loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember to loc_us-gaap_CollaborativeArrangementCopromotionMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_GenzymeCorporationMember" xlink:label="loc_vcyt_GenzymeCorporationMember" xlink:title="GenzymeCorporationMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain" xlink:to="loc_vcyt_GenzymeCorporationMember" xlink:title="Definition : loc_dei_EntityDomain to loc_vcyt_GenzymeCorporationMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredRevenueAbstract" xlink:label="loc_us-gaap_DeferredRevenueAbstract" xlink:title="DeferredRevenueAbstract" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredRevenueCurrent" xlink:label="loc_us-gaap_DeferredRevenueCurrent" xlink:title="DeferredRevenueCurrent" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredRevenueAbstract" xlink:to="loc_us-gaap_DeferredRevenueCurrent" xlink:title="Definition : loc_us-gaap_DeferredRevenueAbstract to loc_us-gaap_DeferredRevenueCurrent" xlink:type="arc" use="optional" order="1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:to="loc_us-gaap_TypeOfArrangementAxis" xlink:title="Definition : loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable to loc_us-gaap_TypeOfArrangementAxis" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="ArrangementsAndNonarrangementTransactionsMember_1" xlink:title="ArrangementsAndNonarrangementTransactionsMember_1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TypeOfArrangementAxis" xlink:to="ArrangementsAndNonarrangementTransactionsMember_1" xlink:title="Definition : loc_us-gaap_TypeOfArrangementAxis to loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.sec.gov/dei/2013/dei-2013-01-31.xsd#dei_EntityDomain" xlink:label="EntityDomain_2" xlink:title="EntityDomain_2" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis" xlink:to="EntityDomain_2" xlink:title="Definition : loc_dei_LegalEntityAxis to loc_dei_EntityDomain" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_CollaborativeArrangementPaymentReceived" xlink:label="loc_vcyt_CollaborativeArrangementPaymentReceived" xlink:title="CollaborativeArrangementPaymentReceived" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_vcyt_CollaborativeArrangementPaymentReceived" xlink:title="Definition : loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems to loc_vcyt_CollaborativeArrangementPaymentReceived" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredRevenueNoncurrent" xlink:label="loc_us-gaap_DeferredRevenueNoncurrent" xlink:title="DeferredRevenueNoncurrent" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredRevenueAbstract" xlink:to="loc_us-gaap_DeferredRevenueNoncurrent" xlink:title="Definition : loc_us-gaap_DeferredRevenueAbstract to loc_us-gaap_DeferredRevenueNoncurrent" xlink:type="arc" use="optional" order="2" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:to="loc_dei_LegalEntityAxis" xlink:title="Definition : loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable to loc_dei_LegalEntityAxis" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_CollaborativeArrangementNumberOfCountriesOutsideUnitedStatesInWhichMarketingAuthorizationIsObtained" xlink:label="loc_vcyt_CollaborativeArrangementNumberOfCountriesOutsideUnitedStatesInWhichMarketingAuthorizationIsObtained" xlink:title="CollaborativeArrangementNumberOfCountriesOutsideUnitedStatesInWhichMarketingAuthorizationIsObtained" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_vcyt_CollaborativeArrangementNumberOfCountriesOutsideUnitedStatesInWhichMarketingAuthorizationIsObtained" xlink:title="Definition : loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems to loc_vcyt_CollaborativeArrangementNumberOfCountriesOutsideUnitedStatesInWhichMarketingAuthorizationIsObtained" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredRevenue" xlink:label="loc_us-gaap_DeferredRevenue" xlink:title="DeferredRevenue" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredRevenueAbstract" xlink:to="loc_us-gaap_DeferredRevenue" xlink:title="Definition : loc_us-gaap_DeferredRevenueAbstract to loc_us-gaap_DeferredRevenue" xlink:type="arc" use="optional" order="3" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:to="loc_us-gaap_RangeAxis" xlink:title="Definition : loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable to loc_us-gaap_RangeAxis" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncreaseDecreaseInDeferredRevenue" xlink:label="loc_us-gaap_IncreaseDecreaseInDeferredRevenue" xlink:title="IncreaseDecreaseInDeferredRevenue" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaap_IncreaseDecreaseInDeferredRevenue" xlink:title="Definition : loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems to loc_us-gaap_IncreaseDecreaseInDeferredRevenue" xlink:type="arc" use="optional" order="4" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="loc_us-gaap_BalanceSheetLocationAxis" xlink:title="BalanceSheetLocationAxis" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:to="loc_us-gaap_BalanceSheetLocationAxis" xlink:title="Definition : loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable to loc_us-gaap_BalanceSheetLocationAxis" xlink:type="arc" use="optional" order="4" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_CollaborativeArrangementAdditionalPaymentsThatMayBeReceived" xlink:label="loc_vcyt_CollaborativeArrangementAdditionalPaymentsThatMayBeReceived" xlink:title="CollaborativeArrangementAdditionalPaymentsThatMayBeReceived" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_vcyt_CollaborativeArrangementAdditionalPaymentsThatMayBeReceived" xlink:title="Definition : loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems to loc_vcyt_CollaborativeArrangementAdditionalPaymentsThatMayBeReceived" xlink:type="arc" use="optional" order="5" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_CollaborativeArrangementAdditionalPaymentsThatMayBeReceivedForEachCountryOutsideUnitedStatesInWhichEntityObtainsMarketingAuthorizationAndAchievesSpecifiedLevelOfReimbursement" xlink:label="loc_vcyt_CollaborativeArrangementAdditionalPaymentsThatMayBeReceivedForEachCountryOutsideUnitedStatesInWhichEntityObtainsMarketingAuthorizationAndAchievesSpecifiedLevelOfReimbursement" xlink:title="CollaborativeArrangementAdditionalPaymentsThatMayBeReceivedForEachCountryOutsideUnitedStatesInWhichEntityObtainsMarketingAuthorizationAndAchievesSpecifiedLevelOfReimbursement" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_vcyt_CollaborativeArrangementAdditionalPaymentsThatMayBeReceivedForEachCountryOutsideUnitedStatesInWhichEntityObtainsMarketingAuthorizationAndAchievesSpecifiedLevelOfReimbursement" xlink:title="Definition : loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems to loc_vcyt_CollaborativeArrangementAdditionalPaymentsThatMayBeReceivedForEachCountryOutsideUnitedStatesInWhichEntityObtainsMarketingAuthorizationAndAchievesSpecifiedLevelOfReimbursement" xlink:type="arc" use="optional" order="6" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_CollaborativeArrangementNumberOfCountriesOutsideUnitedStatesForWhichAdditionalPaymentsMayBeReceived" xlink:label="loc_vcyt_CollaborativeArrangementNumberOfCountriesOutsideUnitedStatesForWhichAdditionalPaymentsMayBeReceived" xlink:title="CollaborativeArrangementNumberOfCountriesOutsideUnitedStatesForWhichAdditionalPaymentsMayBeReceived" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_vcyt_CollaborativeArrangementNumberOfCountriesOutsideUnitedStatesForWhichAdditionalPaymentsMayBeReceived" xlink:title="Definition : loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems to loc_vcyt_CollaborativeArrangementNumberOfCountriesOutsideUnitedStatesForWhichAdditionalPaymentsMayBeReceived" xlink:type="arc" use="optional" order="7" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_CollaborativeArrangementPercentageOfCashReceiptsOfCoPromotionFees" xlink:label="loc_vcyt_CollaborativeArrangementPercentageOfCashReceiptsOfCoPromotionFees" xlink:title="CollaborativeArrangementPercentageOfCashReceiptsOfCoPromotionFees" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_vcyt_CollaborativeArrangementPercentageOfCashReceiptsOfCoPromotionFees" xlink:title="Definition : loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems to loc_vcyt_CollaborativeArrangementPercentageOfCashReceiptsOfCoPromotionFees" xlink:type="arc" use="optional" order="8" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_CollaborativeArrangementPercentageOfCashReceiptsOfCoPromotionFeesForRemainingPeriods" xlink:label="loc_vcyt_CollaborativeArrangementPercentageOfCashReceiptsOfCoPromotionFeesForRemainingPeriods" xlink:title="CollaborativeArrangementPercentageOfCashReceiptsOfCoPromotionFeesForRemainingPeriods" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_vcyt_CollaborativeArrangementPercentageOfCashReceiptsOfCoPromotionFeesForRemainingPeriods" xlink:title="Definition : loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems to loc_vcyt_CollaborativeArrangementPercentageOfCashReceiptsOfCoPromotionFeesForRemainingPeriods" xlink:type="arc" use="optional" order="9" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_CollaborativeArrangementMaximumAmountToBeSpentByCoPromoterForQualifyingClinicalDevelopmentActivitiesInCountriesThatRequireAdditionalTestingForApproval" xlink:label="loc_vcyt_CollaborativeArrangementMaximumAmountToBeSpentByCoPromoterForQualifyingClinicalDevelopmentActivitiesInCountriesThatRequireAdditionalTestingForApproval" xlink:title="CollaborativeArrangementMaximumAmountToBeSpentByCoPromoterForQualifyingClinicalDevelopmentActivitiesInCountriesThatRequireAdditionalTestingForApproval" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_vcyt_CollaborativeArrangementMaximumAmountToBeSpentByCoPromoterForQualifyingClinicalDevelopmentActivitiesInCountriesThatRequireAdditionalTestingForApproval" xlink:title="Definition : loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems to loc_vcyt_CollaborativeArrangementMaximumAmountToBeSpentByCoPromoterForQualifyingClinicalDevelopmentActivitiesInCountriesThatRequireAdditionalTestingForApproval" xlink:type="arc" use="optional" order="10" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_CollaborativeArrangementPriorNoticePeriodForTerminationOfAgreement" xlink:label="loc_vcyt_CollaborativeArrangementPriorNoticePeriodForTerminationOfAgreement" xlink:title="CollaborativeArrangementPriorNoticePeriodForTerminationOfAgreement" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_vcyt_CollaborativeArrangementPriorNoticePeriodForTerminationOfAgreement" xlink:title="Definition : loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems to loc_vcyt_CollaborativeArrangementPriorNoticePeriodForTerminationOfAgreement" xlink:type="arc" use="optional" order="11" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_CollaborativeArrangementCoPromotionFeeAmortizationPeriod" xlink:label="loc_vcyt_CollaborativeArrangementCoPromotionFeeAmortizationPeriod" xlink:title="CollaborativeArrangementCoPromotionFeeAmortizationPeriod" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_vcyt_CollaborativeArrangementCoPromotionFeeAmortizationPeriod" xlink:title="Definition : loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems to loc_vcyt_CollaborativeArrangementCoPromotionFeeAmortizationPeriod" xlink:type="arc" use="optional" order="12" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_CollaborativeArrangementCoPromotionExpenses" xlink:label="loc_vcyt_CollaborativeArrangementCoPromotionExpenses" xlink:title="CollaborativeArrangementCoPromotionExpenses" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_vcyt_CollaborativeArrangementCoPromotionExpenses" xlink:title="Definition : loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems to loc_vcyt_CollaborativeArrangementCoPromotionExpenses" xlink:type="arc" use="optional" order="13" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RecognitionOfDeferredRevenue" xlink:label="loc_us-gaap_RecognitionOfDeferredRevenue" xlink:title="RecognitionOfDeferredRevenue" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaap_RecognitionOfDeferredRevenue" xlink:title="Definition : loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems to loc_us-gaap_RecognitionOfDeferredRevenue" xlink:type="arc" use="optional" order="14" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_CollaborativeArrangementOutstandingObligation" xlink:label="loc_vcyt_CollaborativeArrangementOutstandingObligation" xlink:title="CollaborativeArrangementOutstandingObligation" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_vcyt_CollaborativeArrangementOutstandingObligation" xlink:title="Definition : loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems to loc_vcyt_CollaborativeArrangementOutstandingObligation" xlink:type="arc" use="optional" order="15" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaap_DeferredRevenueAbstract" xlink:title="Definition : loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems to loc_us-gaap_DeferredRevenueAbstract" xlink:type="arc" use="optional" order="16" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain" xlink:title="BalanceSheetLocationDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis" xlink:to="loc_us-gaap_BalanceSheetLocationDomain" xlink:title="Definition : loc_us-gaap_BalanceSheetLocationAxis to loc_us-gaap_BalanceSheetLocationDomain" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccountsPayableMember" xlink:label="loc_us-gaap_AccountsPayableMember" xlink:title="AccountsPayableMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain" xlink:to="loc_us-gaap_AccountsPayableMember" xlink:title="Definition : loc_us-gaap_BalanceSheetLocationDomain to loc_us-gaap_AccountsPayableMember" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_CollaborativeArrangementPercentageOfCoPromotionFeeRepaidTerminationOfAgreementPeriodOne" xlink:label="loc_vcyt_CollaborativeArrangementPercentageOfCoPromotionFeeRepaidTerminationOfAgreementPeriodOne" xlink:title="CollaborativeArrangementPercentageOfCoPromotionFeeRepaidTerminationOfAgreementPeriodOne" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_vcyt_CollaborativeArrangementPercentageOfCoPromotionFeeRepaidTerminationOfAgreementPeriodOne" xlink:title="Definition : loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems to loc_vcyt_CollaborativeArrangementPercentageOfCoPromotionFeeRepaidTerminationOfAgreementPeriodOne" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="BalanceSheetLocationDomain_3" xlink:title="BalanceSheetLocationDomain_3" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis" xlink:to="BalanceSheetLocationDomain_3" xlink:title="Definition : loc_us-gaap_BalanceSheetLocationAxis to loc_us-gaap_BalanceSheetLocationDomain" xlink:type="arc" use="optional" order="8001" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccruedLiabilitiesMember" xlink:label="loc_us-gaap_AccruedLiabilitiesMember" xlink:title="AccruedLiabilitiesMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain" xlink:to="loc_us-gaap_AccruedLiabilitiesMember" xlink:title="Definition : loc_us-gaap_BalanceSheetLocationDomain to loc_us-gaap_AccruedLiabilitiesMember" xlink:type="arc" use="optional" order="8001" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_CollaborativeArrangementPercentageOfCoPromotionFeeRepaidTerminationOfAgreementPeriodTwo" xlink:label="loc_vcyt_CollaborativeArrangementPercentageOfCoPromotionFeeRepaidTerminationOfAgreementPeriodTwo" xlink:title="CollaborativeArrangementPercentageOfCoPromotionFeeRepaidTerminationOfAgreementPeriodTwo" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_vcyt_CollaborativeArrangementPercentageOfCoPromotionFeeRepaidTerminationOfAgreementPeriodTwo" xlink:title="Definition : loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems to loc_vcyt_CollaborativeArrangementPercentageOfCoPromotionFeeRepaidTerminationOfAgreementPeriodTwo" xlink:type="arc" use="optional" order="8001" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_CollaborativeArrangementPercentageOfCoPromotionFeeRepaidTerminationOfAgreementPeriodThree" xlink:label="loc_vcyt_CollaborativeArrangementPercentageOfCoPromotionFeeRepaidTerminationOfAgreementPeriodThree" xlink:title="CollaborativeArrangementPercentageOfCoPromotionFeeRepaidTerminationOfAgreementPeriodThree" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_vcyt_CollaborativeArrangementPercentageOfCoPromotionFeeRepaidTerminationOfAgreementPeriodThree" xlink:title="Definition : loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems to loc_vcyt_CollaborativeArrangementPercentageOfCoPromotionFeeRepaidTerminationOfAgreementPeriodThree" xlink:type="arc" use="optional" order="8002" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/DisclosureThyroidCytologyPartnersDetails">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_VariableInterestEntityLineItems" xlink:label="loc_us-gaap_VariableInterestEntityLineItems" xlink:title="VariableInterestEntityLineItems" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfVariableInterestEntitiesTable" xlink:label="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable" xlink:title="ScheduleOfVariableInterestEntitiesTable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_VariableInterestEntityLineItems" xlink:to="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable" xlink:title="Definition : loc_us-gaap_VariableInterestEntityLineItems to loc_us-gaap_ScheduleOfVariableInterestEntitiesTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis" xlink:label="loc_us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis" xlink:title="VariableInterestEntitiesByClassificationOfEntityAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassificationOfVariableInterestEntityDomain" xlink:label="loc_us-gaap_ClassificationOfVariableInterestEntityDomain" xlink:title="ClassificationOfVariableInterestEntityDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis" xlink:to="loc_us-gaap_ClassificationOfVariableInterestEntityDomain" xlink:title="Definition : loc_us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis to loc_us-gaap_ClassificationOfVariableInterestEntityDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember" xlink:label="loc_us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember" xlink:title="VariableInterestEntityNotPrimaryBeneficiaryMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassificationOfVariableInterestEntityDomain" xlink:to="loc_us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember" xlink:title="Definition : loc_us-gaap_ClassificationOfVariableInterestEntityDomain to loc_us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember" xlink:type="arc" use="optional" order="1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable" xlink:to="loc_us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis" xlink:title="Definition : loc_us-gaap_ScheduleOfVariableInterestEntitiesTable to loc_us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassificationOfVariableInterestEntityDomain" xlink:label="ClassificationOfVariableInterestEntityDomain_1" xlink:title="ClassificationOfVariableInterestEntityDomain_1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis" xlink:to="ClassificationOfVariableInterestEntityDomain_1" xlink:title="Definition : loc_us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis to loc_us-gaap_ClassificationOfVariableInterestEntityDomain" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_TestingAndEvaluationServicesExpense" xlink:label="loc_vcyt_TestingAndEvaluationServicesExpense" xlink:title="TestingAndEvaluationServicesExpense" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems" xlink:to="loc_vcyt_TestingAndEvaluationServicesExpense" xlink:title="Definition : loc_us-gaap_VariableInterestEntityLineItems to loc_vcyt_TestingAndEvaluationServicesExpense" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccountsPayableCurrent" xlink:label="loc_us-gaap_AccountsPayableCurrent" xlink:title="AccountsPayableCurrent" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems" xlink:to="loc_us-gaap_AccountsPayableCurrent" xlink:title="Definition : loc_us-gaap_VariableInterestEntityLineItems to loc_us-gaap_AccountsPayableCurrent" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LeaseAndRentalExpense" xlink:label="loc_us-gaap_LeaseAndRentalExpense" xlink:title="LeaseAndRentalExpense" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems" xlink:to="loc_us-gaap_LeaseAndRentalExpense" xlink:title="Definition : loc_us-gaap_VariableInterestEntityLineItems to loc_us-gaap_LeaseAndRentalExpense" xlink:type="arc" use="optional" order="4" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:title="PrepaidExpenseAndOtherAssetsCurrent" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:title="Definition : loc_us-gaap_VariableInterestEntityLineItems to loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:type="arc" use="optional" order="5" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ExcessPaymentRelatedToTestingAndEvaluationServices" xlink:label="loc_vcyt_ExcessPaymentRelatedToTestingAndEvaluationServices" xlink:title="ExcessPaymentRelatedToTestingAndEvaluationServices" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems" xlink:to="loc_vcyt_ExcessPaymentRelatedToTestingAndEvaluationServices" xlink:title="Definition : loc_us-gaap_VariableInterestEntityLineItems to loc_vcyt_ExcessPaymentRelatedToTestingAndEvaluationServices" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ProfessionalLicensureFees" xlink:label="loc_vcyt_ProfessionalLicensureFees" xlink:title="ProfessionalLicensureFees" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems" xlink:to="loc_vcyt_ProfessionalLicensureFees" xlink:title="Definition : loc_us-gaap_VariableInterestEntityLineItems to loc_vcyt_ProfessionalLicensureFees" xlink:type="arc" use="optional" order="8001" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ProceedsFromReimbursedRent" xlink:label="loc_vcyt_ProceedsFromReimbursedRent" xlink:title="ProceedsFromReimbursedRent" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems" xlink:to="loc_vcyt_ProceedsFromReimbursedRent" xlink:title="Definition : loc_us-gaap_VariableInterestEntityLineItems to loc_vcyt_ProceedsFromReimbursedRent" xlink:type="arc" use="optional" order="8002" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/DisclosureStockIncentivePlansTables">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:title="ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:title="ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems to loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis" xlink:title="AwardTypeAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:title="ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:title="Definition : loc_us-gaap_AwardTypeAxis to loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_EmployeeAndNonEmployeeStockOptionExcludingBonusCompensationMember" xlink:label="loc_vcyt_EmployeeAndNonEmployeeStockOptionExcludingBonusCompensationMember" xlink:title="EmployeeAndNonEmployeeStockOptionExcludingBonusCompensationMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_vcyt_EmployeeAndNonEmployeeStockOptionExcludingBonusCompensationMember" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain to loc_vcyt_EmployeeAndNonEmployeeStockOptionExcludingBonusCompensationMember" xlink:type="arc" use="optional" order="1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="loc_us-gaap_AwardTypeAxis" xlink:title="Definition : loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable to loc_us-gaap_AwardTypeAxis" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" xlink:title="ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems to loc_us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTextBlock" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTextBlock" xlink:title="ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTextBlock" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTextBlock" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems to loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTextBlock" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock" xlink:title="ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems to loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock" xlink:type="arc" use="optional" order="4" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock" xlink:title="ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems to loc_us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock" xlink:type="arc" use="optional" order="5" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_EmployeeStockOptionBonusCompensationMember" xlink:label="loc_vcyt_EmployeeStockOptionBonusCompensationMember" xlink:title="EmployeeStockOptionBonusCompensationMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_vcyt_EmployeeStockOptionBonusCompensationMember" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain to loc_vcyt_EmployeeStockOptionBonusCompensationMember" xlink:type="arc" use="optional" order="8000" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/DisclosureFairValueMeasurementsDetails">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:title="FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:title="FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:title="Definition : loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems to loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueByLiabilityClassAxis" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis" xlink:title="FairValueByLiabilityClassAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:title="FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:title="Definition : loc_us-gaap_FairValueByLiabilityClassAxis to loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis" xlink:title="FairValueByMeasurementFrequencyAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain" xlink:title="FairValueMeasurementFrequencyDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain" xlink:title="Definition : loc_us-gaap_FairValueByMeasurementFrequencyAxis to loc_us-gaap_FairValueMeasurementFrequencyDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:title="FairValueByFairValueHierarchyLevelAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:title="FairValueMeasurementsFairValueHierarchyDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:title="Definition : loc_us-gaap_FairValueByFairValueHierarchyLevelAxis to loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueByAssetClassAxis" xlink:label="loc_us-gaap_FairValueByAssetClassAxis" xlink:title="FairValueByAssetClassAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:title="FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:title="Definition : loc_us-gaap_FairValueByAssetClassAxis to loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LongTermDebtMember" xlink:label="loc_us-gaap_LongTermDebtMember" xlink:title="LongTermDebtMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:to="loc_us-gaap_LongTermDebtMember" xlink:title="Definition : loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain to loc_us-gaap_LongTermDebtMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember" xlink:title="FairValueMeasurementsRecurringMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember" xlink:title="Definition : loc_us-gaap_FairValueMeasurementFrequencyDomain to loc_us-gaap_FairValueMeasurementsRecurringMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member" xlink:title="FairValueInputsLevel1Member" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="loc_us-gaap_FairValueInputsLevel1Member" xlink:title="Definition : loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain to loc_us-gaap_FairValueInputsLevel1Member" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_MoneyMarketFundsMember" xlink:label="loc_us-gaap_MoneyMarketFundsMember" xlink:title="MoneyMarketFundsMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:to="loc_us-gaap_MoneyMarketFundsMember" xlink:title="Definition : loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain to loc_us-gaap_MoneyMarketFundsMember" xlink:type="arc" use="optional" order="1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis" xlink:title="Definition : loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable to loc_us-gaap_FairValueByMeasurementFrequencyAxis" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="FairValueMeasurementFrequencyDomain_1" xlink:title="FairValueMeasurementFrequencyDomain_1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis" xlink:to="FairValueMeasurementFrequencyDomain_1" xlink:title="Definition : loc_us-gaap_FairValueByMeasurementFrequencyAxis to loc_us-gaap_FairValueMeasurementFrequencyDomain" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="FairValueMeasurementsFairValueHierarchyDomain_2" xlink:title="FairValueMeasurementsFairValueHierarchyDomain_2" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="FairValueMeasurementsFairValueHierarchyDomain_2" xlink:title="Definition : loc_us-gaap_FairValueByFairValueHierarchyLevelAxis to loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:label="FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_3" xlink:title="FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_3" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis" xlink:to="FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_3" xlink:title="Definition : loc_us-gaap_FairValueByAssetClassAxis to loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member" xlink:title="FairValueInputsLevel3Member" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="loc_us-gaap_FairValueInputsLevel3Member" xlink:title="Definition : loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain to loc_us-gaap_FairValueInputsLevel3Member" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AssetsFairValueDisclosure" xlink:label="loc_us-gaap_AssetsFairValueDisclosure" xlink:title="AssetsFairValueDisclosure" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="loc_us-gaap_AssetsFairValueDisclosure" xlink:title="Definition : loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems to loc_us-gaap_AssetsFairValueDisclosure" xlink:type="arc" use="optional" order="2" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:title="Definition : loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable to loc_us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember" xlink:title="EstimateOfFairValueFairValueDisclosureMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember" xlink:title="Definition : loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain to loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember" xlink:type="arc" use="optional" order="3" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:to="loc_us-gaap_FairValueByAssetClassAxis" xlink:title="Definition : loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable to loc_us-gaap_FairValueByAssetClassAxis" xlink:type="arc" use="optional" order="3" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis" xlink:title="Definition : loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable to loc_us-gaap_FairValueByLiabilityClassAxis" xlink:type="arc" use="optional" order="4" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_DerivativeFinancialInstrumentsLiabilitiesPreferredStockLiabilityMember" xlink:label="loc_vcyt_DerivativeFinancialInstrumentsLiabilitiesPreferredStockLiabilityMember" xlink:title="DerivativeFinancialInstrumentsLiabilitiesPreferredStockLiabilityMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:to="loc_vcyt_DerivativeFinancialInstrumentsLiabilitiesPreferredStockLiabilityMember" xlink:title="Definition : loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain to loc_vcyt_DerivativeFinancialInstrumentsLiabilitiesPreferredStockLiabilityMember" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member" xlink:title="FairValueInputsLevel2Member" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="loc_us-gaap_FairValueInputsLevel2Member" xlink:title="Definition : loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain to loc_us-gaap_FairValueInputsLevel2Member" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LiabilitiesFairValueDisclosure" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure" xlink:title="LiabilitiesFairValueDisclosure" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosure" xlink:title="Definition : loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems to loc_us-gaap_LiabilitiesFairValueDisclosure" xlink:type="arc" use="optional" order="8000" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/DisclosureFairValueMeasurementsDetails3">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueInputsLiabilitiesQuantitativeInformationLineItems" xlink:label="loc_us-gaap_FairValueInputsLiabilitiesQuantitativeInformationLineItems" xlink:title="FairValueInputsLiabilitiesQuantitativeInformationLineItems" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueInputsLiabilitiesQuantitativeInformationTable" xlink:label="loc_us-gaap_FairValueInputsLiabilitiesQuantitativeInformationTable" xlink:title="FairValueInputsLiabilitiesQuantitativeInformationTable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueInputsLiabilitiesQuantitativeInformationLineItems" xlink:to="loc_us-gaap_FairValueInputsLiabilitiesQuantitativeInformationTable" xlink:title="Definition : loc_us-gaap_FairValueInputsLiabilitiesQuantitativeInformationLineItems to loc_us-gaap_FairValueInputsLiabilitiesQuantitativeInformationTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis" xlink:title="StatementClassOfStockAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain" xlink:title="ClassOfStockDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis" xlink:to="loc_us-gaap_ClassOfStockDomain" xlink:title="Definition : loc_us-gaap_StatementClassOfStockAxis to loc_us-gaap_ClassOfStockDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueByLiabilityClassAxis" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis" xlink:title="FairValueByLiabilityClassAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:title="FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:title="Definition : loc_us-gaap_FairValueByLiabilityClassAxis to loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_SeriesCConvertiblePreferredStockMember" xlink:label="loc_vcyt_SeriesCConvertiblePreferredStockMember" xlink:title="SeriesCConvertiblePreferredStockMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain" xlink:to="loc_vcyt_SeriesCConvertiblePreferredStockMember" xlink:title="Definition : loc_us-gaap_ClassOfStockDomain to loc_vcyt_SeriesCConvertiblePreferredStockMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract" xlink:label="loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract" xlink:title="FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_FairValueAssumptionsProbabilityOfSuccessOfSecondTrancheOfConvertiblePreferredStock" xlink:label="loc_vcyt_FairValueAssumptionsProbabilityOfSuccessOfSecondTrancheOfConvertiblePreferredStock" xlink:title="FairValueAssumptionsProbabilityOfSuccessOfSecondTrancheOfConvertiblePreferredStock" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract" xlink:to="loc_vcyt_FairValueAssumptionsProbabilityOfSuccessOfSecondTrancheOfConvertiblePreferredStock" xlink:title="Definition : loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract to loc_vcyt_FairValueAssumptionsProbabilityOfSuccessOfSecondTrancheOfConvertiblePreferredStock" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_DerivativeFinancialInstrumentsLiabilitiesPreferredStockLiabilityMember" xlink:label="loc_vcyt_DerivativeFinancialInstrumentsLiabilitiesPreferredStockLiabilityMember" xlink:title="DerivativeFinancialInstrumentsLiabilitiesPreferredStockLiabilityMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:to="loc_vcyt_DerivativeFinancialInstrumentsLiabilitiesPreferredStockLiabilityMember" xlink:title="Definition : loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain to loc_vcyt_DerivativeFinancialInstrumentsLiabilitiesPreferredStockLiabilityMember" xlink:type="arc" use="optional" order="1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueInputsLiabilitiesQuantitativeInformationTable" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis" xlink:title="Definition : loc_us-gaap_FairValueInputsLiabilitiesQuantitativeInformationTable to loc_us-gaap_FairValueByLiabilityClassAxis" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_1" xlink:title="FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis" xlink:to="FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_1" xlink:title="Definition : loc_us-gaap_FairValueByLiabilityClassAxis to loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DerivativeLiabilitiesCurrent" xlink:label="loc_us-gaap_DerivativeLiabilitiesCurrent" xlink:title="DerivativeLiabilitiesCurrent" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueInputsLiabilitiesQuantitativeInformationLineItems" xlink:to="loc_us-gaap_DerivativeLiabilitiesCurrent" xlink:title="Definition : loc_us-gaap_FairValueInputsLiabilitiesQuantitativeInformationLineItems to loc_us-gaap_DerivativeLiabilitiesCurrent" xlink:type="arc" use="optional" order="2" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueInputsLiabilitiesQuantitativeInformationTable" xlink:to="loc_us-gaap_StatementClassOfStockAxis" xlink:title="Definition : loc_us-gaap_FairValueInputsLiabilitiesQuantitativeInformationTable to loc_us-gaap_StatementClassOfStockAxis" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueAssumptionsExpectedTerm" xlink:label="loc_us-gaap_FairValueAssumptionsExpectedTerm" xlink:title="FairValueAssumptionsExpectedTerm" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract" xlink:to="loc_us-gaap_FairValueAssumptionsExpectedTerm" xlink:title="Definition : loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract to loc_us-gaap_FairValueAssumptionsExpectedTerm" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueAssumptionsExpectedVolatilityRate" xlink:label="loc_us-gaap_FairValueAssumptionsExpectedVolatilityRate" xlink:title="FairValueAssumptionsExpectedVolatilityRate" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract" xlink:to="loc_us-gaap_FairValueAssumptionsExpectedVolatilityRate" xlink:title="Definition : loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract to loc_us-gaap_FairValueAssumptionsExpectedVolatilityRate" xlink:type="arc" use="optional" order="4" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueInputsLiabilitiesQuantitativeInformationLineItems" xlink:to="loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract" xlink:title="Definition : loc_us-gaap_FairValueInputsLiabilitiesQuantitativeInformationLineItems to loc_us-gaap_FairValueAssumptionsAndMethodologyForAssetsAndLiabilitiesAbstract" xlink:type="arc" use="optional" order="4" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/DisclosureFairValueMeasurementsDetails2">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems" xlink:title="FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:title="FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:title="Definition : loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems to loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueByLiabilityClassAxis" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis" xlink:title="FairValueByLiabilityClassAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:title="FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:title="Definition : loc_us-gaap_FairValueByLiabilityClassAxis to loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis" xlink:title="FairValueByMeasurementFrequencyAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain" xlink:title="FairValueMeasurementFrequencyDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain" xlink:title="Definition : loc_us-gaap_FairValueByMeasurementFrequencyAxis to loc_us-gaap_FairValueMeasurementFrequencyDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:title="FairValueByFairValueHierarchyLevelAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:title="FairValueMeasurementsFairValueHierarchyDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:title="Definition : loc_us-gaap_FairValueByFairValueHierarchyLevelAxis to loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_DerivativeFinancialInstrumentsLiabilitiesPreferredStockLiabilityMember" xlink:label="loc_vcyt_DerivativeFinancialInstrumentsLiabilitiesPreferredStockLiabilityMember" xlink:title="DerivativeFinancialInstrumentsLiabilitiesPreferredStockLiabilityMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:to="loc_vcyt_DerivativeFinancialInstrumentsLiabilitiesPreferredStockLiabilityMember" xlink:title="Definition : loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain to loc_vcyt_DerivativeFinancialInstrumentsLiabilitiesPreferredStockLiabilityMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember" xlink:title="FairValueMeasurementsRecurringMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember" xlink:title="Definition : loc_us-gaap_FairValueMeasurementFrequencyDomain to loc_us-gaap_FairValueMeasurementsRecurringMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member" xlink:title="FairValueInputsLevel3Member" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="loc_us-gaap_FairValueInputsLevel3Member" xlink:title="Definition : loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain to loc_us-gaap_FairValueInputsLevel3Member" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward" xlink:title="FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs" xlink:title="FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs" xlink:title="Definition : loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward to loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs" xlink:type="arc" use="optional" order="1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis" xlink:title="Definition : loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable to loc_us-gaap_FairValueByMeasurementFrequencyAxis" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_DerivativeFinancialInstrumentsLiabilitiesPreferredStockWarrantLiabilityMember" xlink:label="loc_vcyt_DerivativeFinancialInstrumentsLiabilitiesPreferredStockWarrantLiabilityMember" xlink:title="DerivativeFinancialInstrumentsLiabilitiesPreferredStockWarrantLiabilityMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:to="loc_vcyt_DerivativeFinancialInstrumentsLiabilitiesPreferredStockWarrantLiabilityMember" xlink:title="Definition : loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain to loc_vcyt_DerivativeFinancialInstrumentsLiabilitiesPreferredStockWarrantLiabilityMember" xlink:type="arc" use="optional" order="2" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward" xlink:title="Definition : loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems to loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationIssues" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationIssues" xlink:title="FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationIssues" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationIssues" xlink:title="Definition : loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward to loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationIssues" xlink:type="arc" use="optional" order="2" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:title="Definition : loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable to loc_us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings" xlink:title="FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings" xlink:title="Definition : loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward to loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings" xlink:type="arc" use="optional" order="3" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis" xlink:title="Definition : loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable to loc_us-gaap_FairValueByLiabilityClassAxis" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements" xlink:title="FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements" xlink:title="Definition : loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward to loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements" xlink:type="arc" use="optional" order="4" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationConversion" xlink:label="loc_vcyt_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationConversion" xlink:title="FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationConversion" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward" xlink:to="loc_vcyt_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationConversion" xlink:title="Definition : loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward to loc_vcyt_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationConversion" xlink:type="arc" use="optional" order="5" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/DisclosureStockIncentivePlansDetails2">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:title="ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable" xlink:title="ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems to loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:title="ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:title="ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis to loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ExercisePriceDollars0.08Member" xlink:label="loc_vcyt_ExercisePriceDollars0.08Member" xlink:title="ExercisePriceDollars0.08Member" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:to="loc_vcyt_ExercisePriceDollars0.08Member" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain to loc_vcyt_ExercisePriceDollars0.08Member" xlink:type="arc" use="optional" order="1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:title="Definition : loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable to loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_1" xlink:title="ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:to="ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_1" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis to loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ExercisePriceDollars0.80Member" xlink:label="loc_vcyt_ExercisePriceDollars0.80Member" xlink:title="ExercisePriceDollars0.80Member" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:to="loc_vcyt_ExercisePriceDollars0.80Member" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain to loc_vcyt_ExercisePriceDollars0.80Member" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1" xlink:label="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1" xlink:title="SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:to="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems to loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ExercisePriceDollars2.36Member" xlink:label="loc_vcyt_ExercisePriceDollars2.36Member" xlink:title="ExercisePriceDollars2.36Member" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:to="loc_vcyt_ExercisePriceDollars2.36Member" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain to loc_vcyt_ExercisePriceDollars2.36Member" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit" xlink:title="ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems to loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ExercisePriceDollars2.40Member" xlink:label="loc_vcyt_ExercisePriceDollars2.40Member" xlink:title="ExercisePriceDollars2.40Member" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:to="loc_vcyt_ExercisePriceDollars2.40Member" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain to loc_vcyt_ExercisePriceDollars2.40Member" xlink:type="arc" use="optional" order="4" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit" xlink:title="ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems to loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit" xlink:type="arc" use="optional" order="4" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ExercisePriceDollars2.68Member" xlink:label="loc_vcyt_ExercisePriceDollars2.68Member" xlink:title="ExercisePriceDollars2.68Member" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:to="loc_vcyt_ExercisePriceDollars2.68Member" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain to loc_vcyt_ExercisePriceDollars2.68Member" xlink:type="arc" use="optional" order="5" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions" xlink:title="ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems to loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions" xlink:type="arc" use="optional" order="5" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ExercisePriceDollars4.00Member" xlink:label="loc_vcyt_ExercisePriceDollars4.00Member" xlink:title="ExercisePriceDollars4.00Member" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:to="loc_vcyt_ExercisePriceDollars4.00Member" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain to loc_vcyt_ExercisePriceDollars4.00Member" xlink:type="arc" use="optional" order="6" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2" xlink:label="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2" xlink:title="SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:to="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems to loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2" xlink:type="arc" use="optional" order="6" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ExercisePriceDollars6.04Member" xlink:label="loc_vcyt_ExercisePriceDollars6.04Member" xlink:title="ExercisePriceDollars6.04Member" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:to="loc_vcyt_ExercisePriceDollars6.04Member" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain to loc_vcyt_ExercisePriceDollars6.04Member" xlink:type="arc" use="optional" order="7" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions" xlink:title="ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems to loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions" xlink:type="arc" use="optional" order="7" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ExercisePriceDollars7.92Member" xlink:label="loc_vcyt_ExercisePriceDollars7.92Member" xlink:title="ExercisePriceDollars7.92Member" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:to="loc_vcyt_ExercisePriceDollars7.92Member" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain to loc_vcyt_ExercisePriceDollars7.92Member" xlink:type="arc" use="optional" order="8" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageRemainingContractualTerm2" xlink:label="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageRemainingContractualTerm2" xlink:title="SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageRemainingContractualTerm2" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:to="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageRemainingContractualTerm2" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems to loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageRemainingContractualTerm2" xlink:type="arc" use="optional" order="8" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ExercisePriceDollars12.12Member" xlink:label="loc_vcyt_ExercisePriceDollars12.12Member" xlink:title="ExercisePriceDollars12.12Member" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:to="loc_vcyt_ExercisePriceDollars12.12Member" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain to loc_vcyt_ExercisePriceDollars12.12Member" xlink:type="arc" use="optional" order="9" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ExercisePriceRangeFromDollars14.34ToDollars18.24Member" xlink:label="loc_vcyt_ExercisePriceRangeFromDollars14.34ToDollars18.24Member" xlink:title="ExercisePriceRangeFromDollars14.34ToDollars18.24Member" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:to="loc_vcyt_ExercisePriceRangeFromDollars14.34ToDollars18.24Member" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain to loc_vcyt_ExercisePriceRangeFromDollars14.34ToDollars18.24Member" xlink:type="arc" use="optional" order="10" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ExercisePriceRangeFromDollars0.08ToDollars18.24Member" xlink:label="loc_vcyt_ExercisePriceRangeFromDollars0.08ToDollars18.24Member" xlink:title="ExercisePriceRangeFromDollars0.08ToDollars18.24Member" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:to="loc_vcyt_ExercisePriceRangeFromDollars0.08ToDollars18.24Member" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain to loc_vcyt_ExercisePriceRangeFromDollars0.08ToDollars18.24Member" xlink:type="arc" use="optional" order="11" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ExercisePriceRangeFromDollars0.08ToDollars12.12Member" xlink:label="loc_vcyt_ExercisePriceRangeFromDollars0.08ToDollars12.12Member" xlink:title="ExercisePriceRangeFromDollars0.08ToDollars12.12Member" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:to="loc_vcyt_ExercisePriceRangeFromDollars0.08ToDollars12.12Member" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain to loc_vcyt_ExercisePriceRangeFromDollars0.08ToDollars12.12Member" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ExercisePriceRangeFromDollars0.08ToDollars7.92Member" xlink:label="loc_vcyt_ExercisePriceRangeFromDollars0.08ToDollars7.92Member" xlink:title="ExercisePriceRangeFromDollars0.08ToDollars7.92Member" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:to="loc_vcyt_ExercisePriceRangeFromDollars0.08ToDollars7.92Member" xlink:title="Definition : loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain to loc_vcyt_ExercisePriceRangeFromDollars0.08ToDollars7.92Member" xlink:type="arc" use="optional" order="8001" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/DisclosureOrganizationAndSummaryOfSignificantAccountingPoliciesDetails">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ConcentrationRiskLineItems" xlink:label="loc_us-gaap_ConcentrationRiskLineItems" xlink:title="ConcentrationRiskLineItems" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ConcentrationRiskTable" xlink:label="loc_us-gaap_ConcentrationRiskTable" xlink:title="ConcentrationRiskTable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ConcentrationRiskLineItems" xlink:to="loc_us-gaap_ConcentrationRiskTable" xlink:title="Definition : loc_us-gaap_ConcentrationRiskLineItems to loc_us-gaap_ConcentrationRiskTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:title="ConcentrationRiskByBenchmarkAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain" xlink:title="ConcentrationRiskBenchmarkDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain" xlink:title="Definition : loc_us-gaap_ConcentrationRiskByBenchmarkAxis to loc_us-gaap_ConcentrationRiskBenchmarkDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis" xlink:title="ConcentrationRiskByTypeAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain" xlink:title="ConcentrationRiskTypeDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain" xlink:title="Definition : loc_us-gaap_ConcentrationRiskByTypeAxis to loc_us-gaap_ConcentrationRiskTypeDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_HealthCareOrganizationRevenueSourcesAxis" xlink:label="loc_us-gaap_HealthCareOrganizationRevenueSourcesAxis" xlink:title="HealthCareOrganizationRevenueSourcesAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_HealthCareOrganizationRevenueSourcesDomain" xlink:label="loc_us-gaap_HealthCareOrganizationRevenueSourcesDomain" xlink:title="HealthCareOrganizationRevenueSourcesDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HealthCareOrganizationRevenueSourcesAxis" xlink:to="loc_us-gaap_HealthCareOrganizationRevenueSourcesDomain" xlink:title="Definition : loc_us-gaap_HealthCareOrganizationRevenueSourcesAxis to loc_us-gaap_HealthCareOrganizationRevenueSourcesDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SalesRevenueNetMember" xlink:label="loc_us-gaap_SalesRevenueNetMember" xlink:title="SalesRevenueNetMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain" xlink:to="loc_us-gaap_SalesRevenueNetMember" xlink:title="Definition : loc_us-gaap_ConcentrationRiskBenchmarkDomain to loc_us-gaap_SalesRevenueNetMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CustomerConcentrationRiskMember" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember" xlink:title="CustomerConcentrationRiskMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember" xlink:title="Definition : loc_us-gaap_ConcentrationRiskTypeDomain to loc_us-gaap_CustomerConcentrationRiskMember" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_MedicareMember" xlink:label="loc_vcyt_MedicareMember" xlink:title="MedicareMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HealthCareOrganizationRevenueSourcesDomain" xlink:to="loc_vcyt_MedicareMember" xlink:title="Definition : loc_us-gaap_HealthCareOrganizationRevenueSourcesDomain to loc_vcyt_MedicareMember" xlink:type="arc" use="optional" order="1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:title="Definition : loc_us-gaap_ConcentrationRiskTable to loc_us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="ConcentrationRiskBenchmarkDomain_1" xlink:title="ConcentrationRiskBenchmarkDomain_1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:to="ConcentrationRiskBenchmarkDomain_1" xlink:title="Definition : loc_us-gaap_ConcentrationRiskByBenchmarkAxis to loc_us-gaap_ConcentrationRiskBenchmarkDomain" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="ConcentrationRiskTypeDomain_2" xlink:title="ConcentrationRiskTypeDomain_2" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis" xlink:to="ConcentrationRiskTypeDomain_2" xlink:title="Definition : loc_us-gaap_ConcentrationRiskByTypeAxis to loc_us-gaap_ConcentrationRiskTypeDomain" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_HealthCareOrganizationRevenueSourcesDomain" xlink:label="HealthCareOrganizationRevenueSourcesDomain_3" xlink:title="HealthCareOrganizationRevenueSourcesDomain_3" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HealthCareOrganizationRevenueSourcesAxis" xlink:to="HealthCareOrganizationRevenueSourcesDomain_3" xlink:title="Definition : loc_us-gaap_HealthCareOrganizationRevenueSourcesAxis to loc_us-gaap_HealthCareOrganizationRevenueSourcesDomain" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccountsReceivableMember" xlink:label="loc_us-gaap_AccountsReceivableMember" xlink:title="AccountsReceivableMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain" xlink:to="loc_us-gaap_AccountsReceivableMember" xlink:title="Definition : loc_us-gaap_ConcentrationRiskBenchmarkDomain to loc_us-gaap_AccountsReceivableMember" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CreditConcentrationRiskMember" xlink:label="loc_us-gaap_CreditConcentrationRiskMember" xlink:title="CreditConcentrationRiskMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain" xlink:to="loc_us-gaap_CreditConcentrationRiskMember" xlink:title="Definition : loc_us-gaap_ConcentrationRiskTypeDomain to loc_us-gaap_CreditConcentrationRiskMember" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_UnitedHealthcareMember" xlink:label="loc_vcyt_UnitedHealthcareMember" xlink:title="UnitedHealthcareMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HealthCareOrganizationRevenueSourcesDomain" xlink:to="loc_vcyt_UnitedHealthcareMember" xlink:title="Definition : loc_us-gaap_HealthCareOrganizationRevenueSourcesDomain to loc_vcyt_UnitedHealthcareMember" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_NumberOfMajorFinancialInstitutionsWithWhichCashAndCashEquivalentsDeposited" xlink:label="loc_vcyt_NumberOfMajorFinancialInstitutionsWithWhichCashAndCashEquivalentsDeposited" xlink:title="NumberOfMajorFinancialInstitutionsWithWhichCashAndCashEquivalentsDeposited" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems" xlink:to="loc_vcyt_NumberOfMajorFinancialInstitutionsWithWhichCashAndCashEquivalentsDeposited" xlink:title="Definition : loc_us-gaap_ConcentrationRiskLineItems to loc_vcyt_NumberOfMajorFinancialInstitutionsWithWhichCashAndCashEquivalentsDeposited" xlink:type="arc" use="optional" order="2" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis" xlink:title="Definition : loc_us-gaap_ConcentrationRiskTable to loc_us-gaap_ConcentrationRiskByTypeAxis" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_AetnaMember" xlink:label="loc_vcyt_AetnaMember" xlink:title="AetnaMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HealthCareOrganizationRevenueSourcesDomain" xlink:to="loc_vcyt_AetnaMember" xlink:title="Definition : loc_us-gaap_HealthCareOrganizationRevenueSourcesDomain to loc_vcyt_AetnaMember" xlink:type="arc" use="optional" order="3" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1" xlink:title="ConcentrationRiskPercentage1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1" xlink:title="Definition : loc_us-gaap_ConcentrationRiskLineItems to loc_us-gaap_ConcentrationRiskPercentage1" xlink:type="arc" use="optional" order="3" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable" xlink:to="loc_us-gaap_HealthCareOrganizationRevenueSourcesAxis" xlink:title="Definition : loc_us-gaap_ConcentrationRiskTable to loc_us-gaap_HealthCareOrganizationRevenueSourcesAxis" xlink:type="arc" use="optional" order="3" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/DisclosureNetLossPerCommonShareDetails">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" xlink:title="AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" xlink:title="ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" xlink:title="Definition : loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems to loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" xlink:type="arc" use="optional" order="1" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:title="AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain" xlink:title="AntidilutiveSecuritiesNameDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain" xlink:title="Definition : loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis to loc_us-gaap_AntidilutiveSecuritiesNameDomain" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_EmployeeAndNonEmployeeStockOptionMember" xlink:label="loc_vcyt_EmployeeAndNonEmployeeStockOptionMember" xlink:title="EmployeeAndNonEmployeeStockOptionMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain" xlink:to="loc_vcyt_EmployeeAndNonEmployeeStockOptionMember" xlink:title="Definition : loc_us-gaap_AntidilutiveSecuritiesNameDomain to loc_vcyt_EmployeeAndNonEmployeeStockOptionMember" xlink:type="arc" use="optional" order="1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:title="Definition : loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable to loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="AntidilutiveSecuritiesNameDomain_1" xlink:title="AntidilutiveSecuritiesNameDomain_1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:to="AntidilutiveSecuritiesNameDomain_1" xlink:title="Definition : loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis to loc_us-gaap_AntidilutiveSecuritiesNameDomain" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ConvertiblePreferredStockMember" xlink:label="loc_us-gaap_ConvertiblePreferredStockMember" xlink:title="ConvertiblePreferredStockMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain" xlink:to="loc_us-gaap_ConvertiblePreferredStockMember" xlink:title="Definition : loc_us-gaap_AntidilutiveSecuritiesNameDomain to loc_us-gaap_ConvertiblePreferredStockMember" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:title="AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:title="Definition : loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems to loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:type="arc" use="optional" order="2" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_CommonStockWarrantsMember" xlink:label="loc_vcyt_CommonStockWarrantsMember" xlink:title="CommonStockWarrantsMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain" xlink:to="loc_vcyt_CommonStockWarrantsMember" xlink:title="Definition : loc_us-gaap_AntidilutiveSecuritiesNameDomain to loc_vcyt_CommonStockWarrantsMember" xlink:type="arc" use="optional" order="8000" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/DisclosureCommitmentsAndContingenciesDetails">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ScheduleOfOperatingLeasedAssetsTable" xlink:label="loc_us-gaap_ScheduleOfOperatingLeasedAssetsTable" xlink:title="ScheduleOfOperatingLeasedAssetsTable" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis" xlink:title="RangeAxis" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfOperatingLeasedAssetsTable" xlink:to="loc_us-gaap_RangeAxis" xlink:title="Definition : loc_us-gaap_ScheduleOfOperatingLeasedAssetsTable to loc_us-gaap_RangeAxis" xlink:type="arc" use="optional" order="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OperatingLeasedAssetsLineItems" xlink:label="loc_us-gaap_OperatingLeasedAssetsLineItems" xlink:title="OperatingLeasedAssetsLineItems" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OperatingLeasedAssetsLineItems" xlink:to="loc_us-gaap_ScheduleOfOperatingLeasedAssetsTable" xlink:title="Definition : loc_us-gaap_OperatingLeasedAssetsLineItems to loc_us-gaap_ScheduleOfOperatingLeasedAssetsTable" xlink:type="arc" use="optional" order="8000" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember" xlink:title="RangeMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis" xlink:to="loc_us-gaap_RangeMember" xlink:title="Definition : loc_us-gaap_RangeAxis to loc_us-gaap_RangeMember" xlink:type="arc" use="optional" order="8000" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember" xlink:title="MaximumMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember" xlink:to="loc_us-gaap_MaximumMember" xlink:title="Definition : loc_us-gaap_RangeMember to loc_us-gaap_MaximumMember" xlink:type="arc" use="optional" order="8000" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/StatementsOfStockholdersEquityParenthetical">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems" xlink:title="StatementLineItems" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable" xlink:title="StatementTable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems" xlink:to="loc_us-gaap_StatementTable" xlink:title="Definition : loc_us-gaap_StatementLineItems to loc_us-gaap_StatementTable" xlink:type="arc" use="optional" order="10" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis" xlink:title="StatementClassOfStockAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain" xlink:title="ClassOfStockDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis" xlink:to="loc_us-gaap_ClassOfStockDomain" xlink:title="Definition : loc_us-gaap_StatementClassOfStockAxis to loc_us-gaap_ClassOfStockDomain" xlink:type="arc" use="optional" order="10" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_SeriesBConvertiblePreferredStockMember" xlink:label="loc_vcyt_SeriesBConvertiblePreferredStockMember" xlink:title="SeriesBConvertiblePreferredStockMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain" xlink:to="loc_vcyt_SeriesBConvertiblePreferredStockMember" xlink:title="Definition : loc_us-gaap_ClassOfStockDomain to loc_vcyt_SeriesBConvertiblePreferredStockMember" xlink:type="arc" use="optional" order="10" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable" xlink:to="loc_us-gaap_StatementClassOfStockAxis" xlink:title="Definition : loc_us-gaap_StatementTable to loc_us-gaap_StatementClassOfStockAxis" xlink:type="arc" use="optional" order="10" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_SeriesCConvertiblePreferredStockMember" xlink:label="loc_vcyt_SeriesCConvertiblePreferredStockMember" xlink:title="SeriesCConvertiblePreferredStockMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain" xlink:to="loc_vcyt_SeriesCConvertiblePreferredStockMember" xlink:title="Definition : loc_us-gaap_ClassOfStockDomain to loc_vcyt_SeriesCConvertiblePreferredStockMember" xlink:type="arc" use="optional" order="20" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ConvertiblePreferredStockIssuedIssuanceCosts" xlink:label="loc_vcyt_ConvertiblePreferredStockIssuedIssuanceCosts" xlink:title="ConvertiblePreferredStockIssuedIssuanceCosts" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems" xlink:to="loc_vcyt_ConvertiblePreferredStockIssuedIssuanceCosts" xlink:title="Definition : loc_us-gaap_StatementLineItems to loc_vcyt_ConvertiblePreferredStockIssuedIssuanceCosts" xlink:type="arc" use="optional" order="30" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_FairValueOfPreferredStockLiability" xlink:label="loc_vcyt_FairValueOfPreferredStockLiability" xlink:title="FairValueOfPreferredStockLiability" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems" xlink:to="loc_vcyt_FairValueOfPreferredStockLiability" xlink:title="Definition : loc_us-gaap_StatementLineItems to loc_vcyt_FairValueOfPreferredStockLiability" xlink:type="arc" use="optional" order="40" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_CommonStockDiscountOnSharesAndCommissions" xlink:label="loc_vcyt_CommonStockDiscountOnSharesAndCommissions" xlink:title="CommonStockDiscountOnSharesAndCommissions" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems" xlink:to="loc_vcyt_CommonStockDiscountOnSharesAndCommissions" xlink:title="Definition : loc_us-gaap_StatementLineItems to loc_vcyt_CommonStockDiscountOnSharesAndCommissions" xlink:type="arc" use="optional" order="50" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_CommonStockIssuedIssuanceCosts" xlink:label="loc_vcyt_CommonStockIssuedIssuanceCosts" xlink:title="CommonStockIssuedIssuanceCosts" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems" xlink:to="loc_vcyt_CommonStockIssuedIssuanceCosts" xlink:title="Definition : loc_us-gaap_StatementLineItems to loc_vcyt_CommonStockIssuedIssuanceCosts" xlink:type="arc" use="optional" order="60" />
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://www.veracyte.com/role/StatementsOfStockholdersEquity">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems" xlink:title="StatementLineItems" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable" xlink:title="StatementTable" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems" xlink:to="loc_us-gaap_StatementTable" xlink:title="Definition : loc_us-gaap_StatementLineItems to loc_us-gaap_StatementTable" xlink:type="arc" use="optional" order="10" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis" xlink:title="StatementEquityComponentsAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain" xlink:title="EquityComponentDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis" xlink:to="loc_us-gaap_EquityComponentDomain" xlink:title="Definition : loc_us-gaap_StatementEquityComponentsAxis to loc_us-gaap_EquityComponentDomain" xlink:type="arc" use="optional" order="10" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis" xlink:title="StatementClassOfStockAxis" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain" xlink:title="ClassOfStockDomain" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis" xlink:to="loc_us-gaap_ClassOfStockDomain" xlink:title="Definition : loc_us-gaap_StatementClassOfStockAxis to loc_us-gaap_ClassOfStockDomain" xlink:type="arc" use="optional" order="10" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember" xlink:title="CommonStockMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain" xlink:to="loc_us-gaap_CommonStockMember" xlink:title="Definition : loc_us-gaap_EquityComponentDomain to loc_us-gaap_CommonStockMember" xlink:type="arc" use="optional" order="10" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ConvertiblePreferredStockMember" xlink:label="loc_us-gaap_ConvertiblePreferredStockMember" xlink:title="ConvertiblePreferredStockMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain" xlink:to="loc_us-gaap_ConvertiblePreferredStockMember" xlink:title="Definition : loc_us-gaap_ClassOfStockDomain to loc_us-gaap_ConvertiblePreferredStockMember" xlink:type="arc" use="optional" order="10" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_SeriesBConvertiblePreferredStockMember" xlink:label="loc_vcyt_SeriesBConvertiblePreferredStockMember" xlink:title="SeriesBConvertiblePreferredStockMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConvertiblePreferredStockMember" xlink:to="loc_vcyt_SeriesBConvertiblePreferredStockMember" xlink:title="Definition : loc_us-gaap_ConvertiblePreferredStockMember to loc_vcyt_SeriesBConvertiblePreferredStockMember" xlink:type="arc" use="optional" order="10" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward" xlink:label="loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward" xlink:title="IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_StockIssuedDuringPeriodValueConvertiblePreferredStock" xlink:label="loc_vcyt_StockIssuedDuringPeriodValueConvertiblePreferredStock" xlink:title="StockIssuedDuringPeriodValueConvertiblePreferredStock" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward" xlink:to="loc_vcyt_StockIssuedDuringPeriodValueConvertiblePreferredStock" xlink:title="Definition : loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward to loc_vcyt_StockIssuedDuringPeriodValueConvertiblePreferredStock" xlink:type="arc" use="optional" order="10" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_StockIssuedDuringPeriodSharesConvertiblePreferredStock" xlink:label="loc_vcyt_StockIssuedDuringPeriodSharesConvertiblePreferredStock" xlink:title="StockIssuedDuringPeriodSharesConvertiblePreferredStock" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_vcyt_StockIssuedDuringPeriodValueConvertiblePreferredStock" xlink:to="loc_vcyt_StockIssuedDuringPeriodSharesConvertiblePreferredStock" xlink:title="Definition : loc_vcyt_StockIssuedDuringPeriodValueConvertiblePreferredStock to loc_vcyt_StockIssuedDuringPeriodSharesConvertiblePreferredStock" xlink:type="arc" use="optional" order="10" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:title="StockIssuedDuringPeriodValueNewIssues" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:title="StockIssuedDuringPeriodSharesNewIssues" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:title="Definition : loc_us-gaap_StockIssuedDuringPeriodValueNewIssues to loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:type="arc" use="optional" order="10" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ConversionOfStockAmountConverted1" xlink:label="loc_us-gaap_ConversionOfStockAmountConverted1" xlink:title="ConversionOfStockAmountConverted1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ConversionOfStockSharesConverted1" xlink:label="loc_us-gaap_ConversionOfStockSharesConverted1" xlink:title="ConversionOfStockSharesConverted1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConversionOfStockAmountConverted1" xlink:to="loc_us-gaap_ConversionOfStockSharesConverted1" xlink:title="Definition : loc_us-gaap_ConversionOfStockAmountConverted1 to loc_us-gaap_ConversionOfStockSharesConverted1" xlink:type="arc" use="optional" order="10" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" xlink:title="StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:title="StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:title="Definition : loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities to loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:type="arc" use="optional" order="10" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockholdersEquityPeriodIncreaseDecrease" xlink:label="loc_us-gaap_StockholdersEquityPeriodIncreaseDecrease" xlink:title="StockholdersEquityPeriodIncreaseDecrease" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesPeriodIncreaseDecrease" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesPeriodIncreaseDecrease" xlink:title="StockIssuedDuringPeriodSharesPeriodIncreaseDecrease" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityPeriodIncreaseDecrease" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesPeriodIncreaseDecrease" xlink:title="Definition : loc_us-gaap_StockholdersEquityPeriodIncreaseDecrease to loc_us-gaap_StockIssuedDuringPeriodSharesPeriodIncreaseDecrease" xlink:type="arc" use="optional" order="10" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable" xlink:to="loc_us-gaap_StatementClassOfStockAxis" xlink:title="Definition : loc_us-gaap_StatementTable to loc_us-gaap_StatementClassOfStockAxis" xlink:type="arc" use="optional" order="10" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="EquityComponentDomain_1" xlink:title="EquityComponentDomain_1" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis" xlink:to="EquityComponentDomain_1" xlink:title="Definition : loc_us-gaap_StatementEquityComponentsAxis to loc_us-gaap_EquityComponentDomain" xlink:type="arc" use="optional" order="20" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember" xlink:title="AdditionalPaidInCapitalMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember" xlink:title="Definition : loc_us-gaap_EquityComponentDomain to loc_us-gaap_AdditionalPaidInCapitalMember" xlink:type="arc" use="optional" order="20" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_SeriesCConvertiblePreferredStockMember" xlink:label="loc_vcyt_SeriesCConvertiblePreferredStockMember" xlink:title="SeriesCConvertiblePreferredStockMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConvertiblePreferredStockMember" xlink:to="loc_vcyt_SeriesCConvertiblePreferredStockMember" xlink:title="Definition : loc_us-gaap_ConvertiblePreferredStockMember to loc_vcyt_SeriesCConvertiblePreferredStockMember" xlink:type="arc" use="optional" order="20" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems" xlink:to="loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward" xlink:title="Definition : loc_us-gaap_StatementLineItems to loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward" xlink:type="arc" use="optional" order="20" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_ExtinguishmentOfPreferredStockLiability" xlink:label="loc_vcyt_ExtinguishmentOfPreferredStockLiability" xlink:title="ExtinguishmentOfPreferredStockLiability" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward" xlink:to="loc_vcyt_ExtinguishmentOfPreferredStockLiability" xlink:title="Definition : loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward to loc_vcyt_ExtinguishmentOfPreferredStockLiability" xlink:type="arc" use="optional" order="20" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable" xlink:to="loc_us-gaap_StatementEquityComponentsAxis" xlink:title="Definition : loc_us-gaap_StatementTable to loc_us-gaap_StatementEquityComponentsAxis" xlink:type="arc" use="optional" order="20" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:label="loc_us-gaap_RetainedEarningsMember" xlink:title="RetainedEarningsMember" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain" xlink:to="loc_us-gaap_RetainedEarningsMember" xlink:title="Definition : loc_us-gaap_EquityComponentDomain to loc_us-gaap_RetainedEarningsMember" xlink:type="arc" use="optional" order="30" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" xlink:title="StockIssuedDuringPeriodValueStockOptionsExercised" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" xlink:title="Definition : loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward to loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" xlink:type="arc" use="optional" order="30" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:title="Definition : loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward to loc_us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:type="arc" use="optional" order="40" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward" xlink:to="loc_us-gaap_ConversionOfStockAmountConverted1" xlink:title="Definition : loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward to loc_us-gaap_ConversionOfStockAmountConverted1" xlink:type="arc" use="optional" order="50" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" xlink:title="Definition : loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward to loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" xlink:type="arc" use="optional" order="60" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_AdjustmentsToAdditionalPaidInCapitalReclassificationOfPreferredStockWarrantLiability" xlink:label="loc_vcyt_AdjustmentsToAdditionalPaidInCapitalReclassificationOfPreferredStockWarrantLiability" xlink:title="AdjustmentsToAdditionalPaidInCapitalReclassificationOfPreferredStockWarrantLiability" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward" xlink:to="loc_vcyt_AdjustmentsToAdditionalPaidInCapitalReclassificationOfPreferredStockWarrantLiability" xlink:title="Definition : loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward to loc_vcyt_AdjustmentsToAdditionalPaidInCapitalReclassificationOfPreferredStockWarrantLiability" xlink:type="arc" use="optional" order="70" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationEmployee" xlink:label="loc_vcyt_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationEmployee" xlink:title="AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationEmployee" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward" xlink:to="loc_vcyt_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationEmployee" xlink:title="Definition : loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward to loc_vcyt_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationEmployee" xlink:type="arc" use="optional" order="80" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationNonEmployee" xlink:label="loc_vcyt_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationNonEmployee" xlink:title="AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationNonEmployee" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward" xlink:to="loc_vcyt_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationNonEmployee" xlink:title="Definition : loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward to loc_vcyt_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationNonEmployee" xlink:type="arc" use="optional" order="90" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_AdjustmentsToAdditionalPaidInCapitalEquityBasedCompensation" xlink:label="loc_vcyt_AdjustmentsToAdditionalPaidInCapitalEquityBasedCompensation" xlink:title="AdjustmentsToAdditionalPaidInCapitalEquityBasedCompensation" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward" xlink:to="loc_vcyt_AdjustmentsToAdditionalPaidInCapitalEquityBasedCompensation" xlink:title="Definition : loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward to loc_vcyt_AdjustmentsToAdditionalPaidInCapitalEquityBasedCompensation" xlink:type="arc" use="optional" order="100" />
    <link:loc xlink:type="locator" xlink:href="vcyt-20140331.xsd#vcyt_AdjustmentsToAdditionalPaidInCapitalCommonStockSubjectToRepurchase" xlink:label="loc_vcyt_AdjustmentsToAdditionalPaidInCapitalCommonStockSubjectToRepurchase" xlink:title="AdjustmentsToAdditionalPaidInCapitalCommonStockSubjectToRepurchase" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward" xlink:to="loc_vcyt_AdjustmentsToAdditionalPaidInCapitalCommonStockSubjectToRepurchase" xlink:title="Definition : loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward to loc_vcyt_AdjustmentsToAdditionalPaidInCapitalCommonStockSubjectToRepurchase" xlink:type="arc" use="optional" order="110" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TemporaryEquityCarryingAmountAttributableToParent" xlink:label="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent" xlink:title="TemporaryEquityCarryingAmountAttributableToParent" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward" xlink:to="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent" xlink:title="Definition : loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward to loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent" xlink:type="arc" use="optional" order="120" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_TemporaryEquitySharesOutstanding" xlink:label="loc_us-gaap_TemporaryEquitySharesOutstanding" xlink:title="TemporaryEquitySharesOutstanding" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward" xlink:to="loc_us-gaap_TemporaryEquitySharesOutstanding" xlink:title="Definition : loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward to loc_us-gaap_TemporaryEquitySharesOutstanding" xlink:type="arc" use="optional" order="130" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SharesOutstanding" xlink:label="loc_us-gaap_SharesOutstanding" xlink:title="SharesOutstanding" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward" xlink:to="loc_us-gaap_SharesOutstanding" xlink:title="Definition : loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward to loc_us-gaap_SharesOutstanding" xlink:type="arc" use="optional" order="140" />
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward" xlink:to="loc_us-gaap_StockholdersEquityPeriodIncreaseDecrease" xlink:title="Definition : loc_vcyt_IncreaseDecreaseInConvertiblePreferredStockAndStockholdersEquityRollForward to loc_us-gaap_StockholdersEquityPeriodIncreaseDecrease" xlink:type="arc" use="optional" order="150" />
  </link:definitionLink>
</link:linkbase>
