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

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2018-07-26</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001748434</rptOwnerCik>
            <rptOwnerName>REESE DAVID M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>ONE AMGEN CENTER DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>THOUSAND OAKS</rptOwnerCity>
            <rptOwnerState></rptOwnerState>
            <rptOwnerZipCode></rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isOfficer>1</isOfficer>
            <officerTitle>EVP, Research and Development</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>17732</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>58.43</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2012-04-26</value>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2020-04-26</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1480</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Nqso (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>54.69</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2013-04-25</value>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2021-04-25</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2300</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Nqso (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>156.35</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2018-05-03</value>
                <footnoteId id="F5"/>
            </exerciseDate>
            <expirationDate>
                <value>2026-05-03</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>8711</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="F6"/>
            </exerciseDate>
            <expirationDate>
                <value>2027-05-01</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>8714</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="F7"/>
            </exerciseDate>
            <expirationDate>
                <value>2028-04-27</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>7807</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 Company's equity plans: 313 RSUs which vest fully in one installment on 1/30/2019; 686 RSUs which vest in installments of 338 and 348 on 5/3/2019 and 5/3/2020, respectively; 4,920 RSUs which vest in installments of 1,623, 1,624 and 1,673 on 5/1/2019, 5/1/2020 and 5/1/2021, respectively; 984 RSUs which vest in installments of 324, 325 and 335 on 5/1/2019, 5/1/2020 and 5/1/2021, respectively; and 1,014 RSUs which vest in installments of 334, 335 and 345 on 4/27/2020, 4/27/2021 and 4/27/2022, respectively.</footnote>
        <footnote id="F2">These shares include 282 Dividend Equivalents (DEs) granted pursuant to the Amgen Inc. Amended and Restated 2009 Equity Incentive Plan and subject to a qualifying dividend reinvestment plan.  DEs are credited to 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">These options were fully exercisable on 4/26/2014.</footnote>
        <footnote id="F4">These options were fully exercisable on 4/25/2015.</footnote>
        <footnote id="F5">2,874 of these options have vested and the remainder are exercisable in two installments of 2,875 and 2,962 on 5/3/2019 and 5/3/2020, respectively.</footnote>
        <footnote id="F6">These stock options are exercisable in three annual installments of 33%, 33% and 34% on 5/1/2019, 5/1/2020 and 5/1/2021, respectively.</footnote>
        <footnote id="F7">These stock options are exercisable in three annual installments of 33%, 33% and 34% on 4/27/2020, 4/27/2021 and 4/27/2022, respectively.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ David M. Reese</signatureName>
        <signatureDate>2018-08-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
