<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2022-03-14</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000318154</issuerCik>
        <issuerName>AMGEN INC</issuerName>
        <issuerTradingSymbol>AMGN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001917312</rptOwnerCik>
            <rptOwnerName>Miller Derek</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>ONE AMGEN CENTER DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>THOUSAND OAKS</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>91320</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isOfficer>1</isOfficer>
            <officerTitle>SVP, Human Resources</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5843</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Nqso (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>156.35</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2018-05-03</value>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2026-05-03</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1524</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Nqso (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>162.60</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2019-05-01</value>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2027-05-02</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2069</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Nqso (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>177.46</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2020-04-27</value>
                <footnoteId id="F5"/>
            </exerciseDate>
            <expirationDate>
                <value>2028-04-27</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1821</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Nqso (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>177.31</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2021-05-03</value>
                <footnoteId id="F6"/>
            </exerciseDate>
            <expirationDate>
                <value>2029-05-03</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>3692</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Nqso (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>236.36</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2022-05-05</value>
                <footnoteId id="F7"/>
            </exerciseDate>
            <expirationDate>
                <value>2030-05-05</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>3365</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Nqso (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>239.64</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2023-04-30</value>
                <footnoteId id="F8"/>
            </exerciseDate>
            <expirationDate>
                <value>2031-04-30</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>3405</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">These shares include the following Restricted Stock Units (RSUs) granted under the Amgen Inc. 2009 Equity Incentive Plan: 81 RSUs which will vest on 4/27/2022; 614 RSUs which will vest on 4/27/2022; 283 RSUs which vest in
installments of 139 on 5/3/2022 and 144 on 5/3/2023; 401 RSUs which vest in two installments of 132 on 5/5/2022 and 5/5/2023 and one installment of 137 on 5/5/2024; 392 RSUs which vest in two installments of 129 on 4/30/2023 and on 4/30/2024 and 134 on 4/30/2025; and 350 RSUs which vest in two installments of 175 on 11/5/2022 and 11/5/2023. Vested RSUs will be paid in shares of the Company's common stock on a one-to-one basis.</footnote>
        <footnote id="F2">These shares include 157 Dividend Equivalents (DEs) granted pursuant to the Amgen Inc. 2009 Equity Incentive Plan and subject to a qualifying dividend reinvestment plan. DEs are credited on the reporting person's unvested RSUs
and are paid out in shares of the Company's common stock on a one-to-one basis according to the vesting schedule, along with a cash payment for any remaining fractional share amount.</footnote>
        <footnote id="F3">1,524 of these non-qualified stock options have vested and are exercisable.</footnote>
        <footnote id="F4">2,069 of these non-qualified stock options have vested and are exercisable.</footnote>
        <footnote id="F5">1,201 of these non-qualified stock options have vested and are exercisable and 620 of these options will vest and become exercisable on 4/27/2022.</footnote>
        <footnote id="F6">1,218 of these non-qualified stock options have vested and are exercisable and the remaining options will vest and become exercisable in installments of 1,218 on 5/3/2022 and 1,256 on 5/3/2023.</footnote>
        <footnote id="F7">These non-qualified stock options will vest and become exercisable in two installments of 1,110 on 5/5/2022 and 5/5/2023 and one installment of 1,145 on 5/5/2024.</footnote>
        <footnote id="F8">These non-qualified stock options will vest and become exercisable in three installments of 1,123 on 4/30/2023, 1,124 on 4/30/2024 and 1,158 on 4/30/2025.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Derek Miller</signatureName>
        <signatureDate>2022-03-17</signatureDate>
    </ownerSignature>
</ownershipDocument>
