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  <xs:element id="ilmn_ContingentValueRightFairValueDisclosure" abstract="false" name="ContingentValueRightFairValueDisclosure" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ilmn_HelixContingentConsiderationMember" abstract="true" name="HelixContingentConsiderationMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="ilmn_BusinessCombinationContingentConsiderationLiabilityMember" abstract="true" name="BusinessCombinationContingentConsiderationLiabilityMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ilmn_TermNotesMember" abstract="true" name="TermNotesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ilmn_TermNotesDue2025Member" abstract="true" name="TermNotesDue2025Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ilmn_TermNotesDue2026Member" abstract="true" name="TermNotesDue2026Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="ilmn_TermNotesDue2027Member" abstract="true" name="TermNotesDue2027Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ilmn_TermNotesDue2031Member" abstract="true" name="TermNotesDue2031Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ilmn_DelayedDrawCreditFacilityDue2025Member" abstract="true" name="DelayedDrawCreditFacilityDue2025Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="ilmn_RevolvingCreditAgreementMember" abstract="true" name="RevolvingCreditAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="ilmn_SwinglineBorrowingsMember" abstract="true" name="SwinglineBorrowingsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ilmn_DebtInstrumentNumberOfOneYearExtensions" abstract="false" name="DebtInstrumentNumberOfOneYearExtensions" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="ilmn_DebtInstrumentExtensionTerm" abstract="false" name="DebtInstrumentExtensionTerm" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="ilmn_DebtInstrumentFaceAmountOptionalIncreaseInAdditionalBorrowings" abstract="false" name="DebtInstrumentFaceAmountOptionalIncreaseInAdditionalBorrowings" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ilmn_DebtInstrumentNumberOfConsecutiveFiscalQuartersMinimumDebtToEBITDARatio" abstract="false" name="DebtInstrumentNumberOfConsecutiveFiscalQuartersMinimumDebtToEBITDARatio" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="ilmn_DebtInstrumentCovenantMinimumDebtToEBITDARatio" abstract="false" name="DebtInstrumentCovenantMinimumDebtToEBITDARatio" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="ilmn_DebtInstrumentCovenantMinimumDebtToEBITDARatioUponConsummationOfAcquisition" abstract="false" name="DebtInstrumentCovenantMinimumDebtToEBITDARatioUponConsummationOfAcquisition" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="ilmn_DebtInstrumentNumberOfConsecutiveFiscalQuartersMinimumDebtToEBITDARatioUponConsummationOfAcquisition" abstract="false" name="DebtInstrumentNumberOfConsecutiveFiscalQuartersMinimumDebtToEBITDARatioUponConsummationOfAcquisition" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="ilmn_A2015StockAndIncentiveCompensationPlanMember" abstract="true" name="A2015StockAndIncentiveCompensationPlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ilmn_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantPeriodAdjustment" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantPeriodAdjustment" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="ilmn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdjustmentsInPeriod" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdjustmentsInPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="ilmn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdjustmentsInPeriodWeightedAverageGrantDateFairValue" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdjustmentsInPeriodWeightedAverageGrantDateFairValue" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:perShareItemType"/>
  <xs:element id="ilmn_ShareBasedPaymentArrangementPerformanceOptionsMember" abstract="true" name="ShareBasedPaymentArrangementPerformanceOptionsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ilmn_LiabilityBasedAwardsMember" abstract="true" name="LiabilityBasedAwardsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ilmn_ShareBasedCompensationArrangementByShareBasedPaymentAwardLiabilityClassifiedAwardsOutstandingRollForward" abstract="true" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardLiabilityClassifiedAwardsOutstandingRollForward" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="ilmn_ShareBasedCompensationArrangementByShareBasedPaymentAwardLiabilityClassifiedAwardsOutstandingValue" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardLiabilityClassifiedAwardsOutstandingValue" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ilmn_ShareBasedCompensationArrangementByShareBasedPaymentAwardLiabilityClassifiedAwardsGrantedValue" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardLiabilityClassifiedAwardsGrantedValue" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ilmn_ShareBasedCompensationArrangementByShareBasedPaymentAwardLiabilityClassifiedAwardsVestedAndPaidInCashValue" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardLiabilityClassifiedAwardsVestedAndPaidInCashValue" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ilmn_ShareBasedCompensationArrangementByShareBasedPaymentAwardLiabilityClassifiedAwardsForfeitedValue" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardLiabilityClassifiedAwardsForfeitedValue" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ilmn_ShareBasedCompensationArrangementByShareBasedPaymentAwardChangeInFairValue" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardChangeInFairValue" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ilmn_ShareBasedCompensationArrangementByShareBasedPaymentAwardLiabilityClassifiedAwardsDerecognition" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardLiabilityClassifiedAwardsDerecognition" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ilmn_AccruedLiabilityClassifiedAwardsCurrent" abstract="false" name="AccruedLiabilityClassifiedAwardsCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ilmn_ShareBasedCompensationArrangementByShareBasedPaymentAwardLiabilityClassifiedAwardAggregateIntrinsicValueNonvested" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardLiabilityClassifiedAwardAggregateIntrinsicValueNonvested" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ilmn_A2000EmployeeStockPurchasePlanMember" abstract="true" name="A2000EmployeeStockPurchasePlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ilmn_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantPeriodIncrease" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantPeriodIncrease" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="ilmn_CostOfGoodsSoldMember" abstract="true" name="CostOfGoodsSoldMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ilmn_CostOfServicesMember" abstract="true" name="CostOfServicesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ilmn_StandardProductWarrantyDescriptionTerm" abstract="false" name="StandardProductWarrantyDescriptionTerm" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="ilmn_AssetImpairmentChargesMember" abstract="true" name="AssetImpairmentChargesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="ilmn_MeasurementInputCashFlowPeriodMember" abstract="true" name="MeasurementInputCashFlowPeriodMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="ilmn_FluentBioSciencesMember" abstract="true" name="FluentBioSciencesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="ilmn_GoodwillAmountThatExceedsCarryingValue" abstract="false" name="GoodwillAmountThatExceedsCarryingValue" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ilmn_GoodwillImpairmentMeasurementInput" abstract="false" name="GoodwillImpairmentMeasurementInput" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="ilmn_SensitivityAnalysisOfGoodwillImpairmentAdditionalChargesImpactOf50BasisPoints" abstract="false" name="SensitivityAnalysisOfGoodwillImpairmentAdditionalChargesImpactOf50BasisPoints" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ilmn_SensitivityAnalysisOfGoodwillImpairmentAdditionalChargesImpactOf100BasisPoints" abstract="false" name="SensitivityAnalysisOfGoodwillImpairmentAdditionalChargesImpactOf100BasisPoints" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ilmn_IntangibleAssetsImpairmentMeasurementInput" abstract="false" name="IntangibleAssetsImpairmentMeasurementInput" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="ilmn_SensitivityAnalysisOfIntangibleAssetsImpairmentAdditionalChargesImpactOf300BasisPoints" abstract="false" name="SensitivityAnalysisOfIntangibleAssetsImpairmentAdditionalChargesImpactOf300BasisPoints" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ilmn_LicensedTechnologyMember" abstract="true" name="LicensedTechnologyMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="ilmn_IndefiniteLivedIntangibleAssetsExcludingGoodwillGross" abstract="false" name="IndefiniteLivedIntangibleAssetsExcludingGoodwillGross" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ilmn_FiniteLivedIntangibleAssetExpectedAmortizationAfterYearFour" abstract="false" name="FiniteLivedIntangibleAssetExpectedAmortizationAfterYearFour" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ilmn_DerivativeNotionalAmountDisposedOf" abstract="false" name="DerivativeNotionalAmountDisposedOf" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="ilmn_AcquisitionOfGrailInc.Member" abstract="true" name="AcquisitionOfGrailInc.Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="ilmn_LitigationSettlementFinePercentageRate" abstract="false" name="LitigationSettlementFinePercentageRate" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="ilmn_CommitmentsAndContingenciesNumberOfMovantsFiledMotionsConsolidateActions" abstract="false" name="CommitmentsAndContingenciesNumberOfMovantsFiledMotionsConsolidateActions" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="ilmn_CommitmentsAndContingenciesNumberOfAdditionalSecuritiesClassActions" abstract="false" name="CommitmentsAndContingenciesNumberOfAdditionalSecuritiesClassActions" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="ilmn_CoreIlluminaMember" abstract="true" name="CoreIlluminaMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
</xs:schema>
