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  <xsd:element abstract="true" id="regn_A487PatentMember" name="A487PatentMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
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  <xsd:element abstract="true" id="regn_A741PatentMember" name="A741PatentMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_AccountingStandardsUpdate201409And201601Member" name="AccountingStandardsUpdate201409And201601Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_AccruedCapitalExpenditures" name="AccruedCapitalExpenditures" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="regn_AccruedClinicalTrialExpenseCurrent" name="AccruedClinicalTrialExpenseCurrent" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="regn_Accruedsalesrelatedchargesdeductionsandroyalties" name="Accruedsalesrelatedchargesdeductionsandroyalties" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="regn_AdditionalSharesRegistered" name="AdditionalSharesRegistered" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Additionalyearstoextendtheagreement" name="Additionalyearstoextendtheagreement" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_AggregatePaymentReceivedWithRegardsToAmendment" name="AggregatePaymentReceivedWithRegardsToAmendment" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="regn_AggregatefuturedevelopmentmilestonepaymentstheCompanyiseligibletoreceive" name="AggregatefuturedevelopmentmilestonepaymentstheCompanyiseligibletoreceive" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_AlnylamPharmaceuticalsInc.CollaborationAgreementMember" name="AlnylamPharmaceuticalsInc.CollaborationAgreementMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_AlnylamPharmaceuticalsInc.StockPurchaseAgreementMember" name="AlnylamPharmaceuticalsInc.StockPurchaseAgreementMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_AmendedIODiscoveryAgreementBCMAxCD3ProgramMember" name="AmendedIODiscoveryAgreementBCMAxCD3ProgramMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
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  <xsd:element abstract="true" id="regn_AmendedRestatedLongTermIncentivePlan2014Member" name="AmendedRestatedLongTermIncentivePlan2014Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_Amgenv.s.RegeneronMember" name="Amgenv.s.RegeneronMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_AmountRelatedToObligationToPayGrossProfitsSharing" name="AmountRelatedToObligationToPayGrossProfitsSharing" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_AmountsRecognizedInConnectionWithUpFrontPaymentsMember" name="AmountsRecognizedInConnectionWithUpFrontPaymentsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_AnnualFundingMaximumOfResearchActivitiesPerAmendedAgreement" name="AnnualFundingMaximumOfResearchActivitiesPerAmendedAgreement" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ArcalystNetProductSalesMember" name="ArcalystNetProductSalesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_AssetsAndLiabilitiesLesseeTableTextBlock" name="AssetsAndLiabilitiesLesseeTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_AvailableForSaleEquitySecuritiesNetUnrealizedGainsLossesRecognizedInOtherComprehensiveIncomeLoss" name="AvailableForSaleEquitySecuritiesNetUnrealizedGainsLossesRecognizedInOtherComprehensiveIncomeLoss" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_BayerCollaborationAgreementMember" name="BayerCollaborationAgreementMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_BayerTevaPharmaceuticalsAndOtherAgreementsMember" name="BayerTevaPharmaceuticalsAndOtherAgreementsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
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  <xsd:element id="regn_CollaborationRevenueForNonRefundableUpFrontPaymentsDevelopmentMilestonesAndPaymentsForDevelopmentActivitiesForWhichUsedAnInputMethod" name="CollaborationRevenueForNonRefundableUpFrontPaymentsDevelopmentMilestonesAndPaymentsForDevelopmentActivitiesForWhichUsedAnInputMethod" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_CollaborationandContractManufacturingMember" name="CollaborationandContractManufacturingMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_CollaborativeArrangementAdditionalEligibleAggregatePayments" name="CollaborativeArrangementAdditionalEligibleAggregatePayments" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
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  <xsd:element id="regn_Contingentreimbursementobligation" name="Contingentreimbursementobligation" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element id="regn_ContractWithCustomerAssetLiabilityNet" name="ContractWithCustomerAssetLiabilityNet" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
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  <xsd:element id="regn_DepreciationDepletionAndAmortizationExcludingIntangibleAssets" name="DepreciationDepletionAndAmortizationExcludingIntangibleAssets" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_DistributionRelatedFeesMember" name="DistributionRelatedFeesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_EffectiveIncomeTaxRateReconciliationDeductionForeignIntangibleIncomePercent" name="EffectiveIncomeTaxRateReconciliationDeductionForeignIntangibleIncomePercent" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_EffectiveIncomeTaxRateReconciliationSaleOfNonInventoryRelatedAssetsBetweenForeignSubsidiariesPercent" name="EffectiveIncomeTaxRateReconciliationSaleOfNonInventoryRelatedAssetsBetweenForeignSubsidiariesPercent" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_EndingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCollaboratingParty" name="EndingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCollaboratingParty" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_EndingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCompany" name="EndingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCompany" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ExcessShareOfProfitNotRequiredToToBeAppliedToReimburseDevelopmentCost" name="ExcessShareOfProfitNotRequiredToToBeAppliedToReimburseDevelopmentCost" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ExpenditureCostsCap" name="ExpenditureCostsCap" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="regn_ExtensionOfResearchTermFee" name="ExtensionOfResearchTermFee" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
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  <xsd:element id="regn_FinanceLeaseCost" name="FinanceLeaseCost" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="regn_FinanceLeaseRemainingLeaseTerm" name="FinanceLeaseRemainingLeaseTerm" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_FinanceLeaseRightofUseAssetAccumulatedAmortization" name="FinanceLeaseRightofUseAssetAccumulatedAmortization" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element id="regn_FundingMaximumofResearchActivitiesPerAgreement" name="FundingMaximumofResearchActivitiesPerAgreement" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="regn_FurnitureOfficeEquipmentAndOtherMember" name="FurnitureOfficeEquipmentAndOtherMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_GainContingencyClaimsInvalidatedNumber" name="GainContingencyClaimsInvalidatedNumber" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="instant" />
  <xsd:element id="regn_GainContingencyInterPartesReviewFiledNumber" name="GainContingencyInterPartesReviewFiledNumber" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_GrossSalesRevenueMember" name="GrossSalesRevenueMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
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  <xsd:element abstract="true" id="regn_IOLicenseandCollaborationAgreementMember" name="IOLicenseandCollaborationAgreementMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_InitialResearchTerm" name="InitialResearchTerm" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_January12024ThroughDecember312026Member" name="January12024ThroughDecember312026Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
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  <xsd:element id="regn_LesseeFinanceLeaseLiabilityDebtFinancingCosts" name="LesseeFinanceLeaseLiabilityDebtFinancingCosts" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="regn_LesseeOperatingLeaseLiabilityDebtFinancingCosts" name="LesseeOperatingLeaseLiabilityDebtFinancingCosts" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="regn_Levelsoftwelvemonthsalesatwhichsalesmilestonepaymentswouldbereceived" name="Levelsoftwelvemonthsalesatwhichsalesmilestonepaymentswouldbereceived" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="regn_Licenseagreementterm" name="Licenseagreementterm" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_LineofCreditFacilityIncreaseLimit" name="LineofCreditFacilityIncreaseLimit" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
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  <xsd:element id="regn_NumberOfSharesTheCollaboratorAvailableToSell" name="NumberOfSharesTheCollaboratorAvailableToSell" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="instant" />
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  <xsd:element id="regn_NumberofNewlyIssuedSharesPurchased" name="NumberofNewlyIssuedSharesPurchased" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_OptionalPaymentToIncreaseDevelopmentCostFunding" name="OptionalPaymentToIncreaseDevelopmentCostFunding" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_OtherAgreementsMember" name="OtherAgreementsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_OtherCollaborationAgreementsMember" name="OtherCollaborationAgreementsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_OtherMember" name="OtherMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_OtherSalesRelatedDeductionsMember" name="OtherSalesRelatedDeductionsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_PD1Member" name="PD1Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PaymentsForRoyaltiesPercentage" name="PaymentsForRoyaltiesPercentage" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PaymentsMadeToAcquireEquityWithinACollaborationAgreement" name="PaymentsMadeToAcquireEquityWithinACollaborationAgreement" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="regn_PercentageOfOutstandingSharesOrVotingRightsUnderAmendedInvestorAgreement" name="PercentageOfOutstandingSharesOrVotingRightsUnderAmendedInvestorAgreement" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant" />
  <xsd:element id="regn_PercentageOfOutstandingSharesThatTheCompanyIsRequiredToAppointAnIndividualAgreedUponByTheCompanyAndTheCollaboratorToTheCompanysBoardOfDirectors" name="PercentageOfOutstandingSharesThatTheCompanyIsRequiredToAppointAnIndividualAgreedUponByTheCompanyAndTheCollaboratorToTheCompanysBoardOfDirectors" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant" />
  <xsd:element id="regn_PercentageOfTrialCostsBorneByCollaboratingParty" name="PercentageOfTrialCostsBorneByCollaboratingParty" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PercentageOfTrialCostsBorneByEntity" name="PercentageOfTrialCostsBorneByEntity" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PercentageOfTrialCostsToBeReimbursedDueToProfitabilityOfAgreement" name="PercentageOfTrialCostsToBeReimbursedDueToProfitabilityOfAgreement" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Percentageofrepaymentofdevelopmentbalanceoutofprofits" name="Percentageofrepaymentofdevelopmentbalanceoutofprofits" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PeriodForAchievingSalesTargetForMilestonePaymentRollingBasis" name="PeriodForAchievingSalesTargetForMilestonePaymentRollingBasis" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PeriodOfNoticeToOptOutOfFurtherDevelopmentAndOrCommercialization" name="PeriodOfNoticeToOptOutOfFurtherDevelopmentAndOrCommercialization" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PotentialExtensionOfResearchTerm" name="PotentialExtensionOfResearchTerm" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PotentialMaximumExpenditure" name="PotentialMaximumExpenditure" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element id="regn_PotentialfutureRDexpenses" name="PotentialfutureRDexpenses" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_PraluentKevzaraandDupixentMemberMember" name="PraluentKevzaraandDupixentMemberMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_PriorCreditAgreementMember" name="PriorCreditAgreementMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization" name="PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="regn_RebatesAndChargebacksMember" name="RebatesAndChargebacksMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ReimbursementForManufacturingOfCommercialSuppliesMember" name="ReimbursementForManufacturingOfCommercialSuppliesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ReimbursementOfCommercializationRelatedExpensesMember" name="ReimbursementOfCommercializationRelatedExpensesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ReimbursementOfResearchAndDevelopmentExpensesMember" name="ReimbursementOfResearchAndDevelopmentExpensesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ResearchAndDevelopmentArrangementContractToPerformForOthersByProductAxis" name="ResearchAndDevelopmentArrangementContractToPerformForOthersByProductAxis" nillable="true" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ResearchAndDevelopmentArrangementContractToPerformForOthersByProductDomain" name="ResearchAndDevelopmentArrangementContractToPerformForOthersByProductDomain" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ResearchCollaborationAndLicensingAgreementsAxis" name="ResearchCollaborationAndLicensingAgreementsAxis" nillable="true" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ResearchCollaborationAndLicensingAgreementsDomain" name="ResearchCollaborationAndLicensingAgreementsDomain" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ResearchCollaborationAndLicensingArrangementsLineItems" name="ResearchCollaborationAndLicensingArrangementsLineItems" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ResearchCollaborationAndLicensingArrangementsTable" name="ResearchCollaborationAndLicensingArrangementsTable" nillable="true" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_RestrictedMember" name="RestrictedMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_RevenueFromContractWithCustomerPeriodPriorToProductsExpirationDateForReturnsAccepted" name="RevenueFromContractWithCustomerPeriodPriorToProductsExpirationDateForReturnsAccepted" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_RevenueFromContractWithCustomerPeriodUpToProductsExpirationDateForReturnsAccepted" name="RevenueFromContractWithCustomerPeriodUpToProductsExpirationDateForReturnsAccepted" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_RevenueRecognitionDevelopmentMilestoneAchieved" name="RevenueRecognitionDevelopmentMilestoneAchieved" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="regn_RevenuebasedonpercentageofannualsalesinJapan" name="RevenuebasedonpercentageofannualsalesinJapan" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_RoyaltyRateMaximum" name="RoyaltyRateMaximum" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_RoyaltyRateMinimum" name="RoyaltyRateMinimum" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_SanofiCollaborationAgreementAntibodyMember" name="SanofiCollaborationAgreementAntibodyMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_SanofiCollaborationAgreementImmunooncologyMember" name="SanofiCollaborationAgreementImmunooncologyMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_SanofiCollaborationAgreementMember" name="SanofiCollaborationAgreementMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ScheduleOfSalesRelatedDeductionsActivityTableTextBlock" name="ScheduleOfSalesRelatedDeductionsActivityTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ShareBasedCompensationArrangementByShareBasedPaymentAwardExpiration" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardExpiration" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ShareBasedCompensationArrangementByShareBasedPaymentAwardPeriodFromVestingDateAwardsMayBeReceived" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardPeriodFromVestingDateAwardsMayBeReceived" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ShareOfLossesOutsideUnitedStatesForCollaboratingParty" name="ShareOfLossesOutsideUnitedStatesForCollaboratingParty" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ShareOfLossesOutsideUnitedStatesForCompany" name="ShareOfLossesOutsideUnitedStatesForCompany" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ShareOfProfitsLossesInConnectionWithCommercializationMember" name="ShareOfProfitsLossesInConnectionWithCommercializationMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_StartingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCollaboratingParty" name="StartingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCollaboratingParty" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_StartingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCompany" name="StartingShareOfProfitsOutsideUnitedStatesBasedOnSalesForCompany" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_StockIssuedDistributedDuringPeriodSharesEmployeeBenefitPlan" name="StockIssuedDistributedDuringPeriodSharesEmployeeBenefitPlan" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_StockIssuedDistributedDuringPeriodValueEmployeeBenefitPlan" name="StockIssuedDistributedDuringPeriodValueEmployeeBenefitPlan" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_TevaPharmaceuticalsCollaborationAgreementMember" name="TevaPharmaceuticalsCollaborationAgreementMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ThreeIndividualCustomersMember" name="ThreeIndividualCustomersMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ThroughDecember312023Member" name="ThroughDecember312023Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_UnrecognizedTaxBenefitsDecreaseResultingFromSettlementsWithTaxingAuthoritiesAndReductionResultingFromLapseOfApplicableStatuteOfLimitations" name="UnrecognizedTaxBenefitsDecreaseResultingFromSettlementsWithTaxingAuthoritiesAndReductionResultingFromLapseOfApplicableStatuteOfLimitations" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_UnrestrictedMember" name="UnrestrictedMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_UpfrontPaymentMade" name="UpfrontPaymentMade" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="regn_Upfrontpaymentreceived" name="Upfrontpaymentreceived" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
</xsd:schema>
