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

    <schemaVersion>X0101</schemaVersion>

<documentType>4/A</documentType>
    <periodOfReport>2003-05-14</periodOfReport>
    <dateOfOriginalSubmission>2003-05-15</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>
<issuer>        <issuerCik>0001085913</issuerCik>
        <issuerName>FARMERS &amp; MERCHANTS BANCORP</issuerName>
<issuerTradingSymbol>FMCB</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
    <reportingOwnerId>
        <rptOwnerCik>0001184708</rptOwnerCik>
            <rptOwnerName>ADAMS STEWART C JR</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
<reportingOwnerRelationship>
        <isDirector>1</isDirector>
        <isOfficer>0</isOfficer>
        <isTenPercentOwner>0</isTenPercentOwner>
        <isOther>0</isOther>
    </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeSecurity>
        <securityTitle>
            <value>Common Stock</value>
        </securityTitle>
        <transactionDate>
            <value>2003-05-14</value>
        </transactionDate>
    <transactionCoding>
        <transactionFormType>4</transactionFormType>
        <transactionCode>J</transactionCode>
        <equitySwapInvolved>0</equitySwapInvolved>
        <footnoteId id="F1"/>
    </transactionCoding>
        <transactionAmounts>
            <transactionShares>
                <value>75</value>
            </transactionShares>
            <transactionValue>
                <value>0</value>
                <footnoteId id="F1"/>
            </transactionValue>
            <transactionAcquiredDisposedCode>
                <value>A</value>
            </transactionAcquiredDisposedCode>
        </transactionAmounts>
        <postTransactionAmounts>
            <sharesOwnedFollowingTransaction>
                <value>1594</value>
            </sharesOwnedFollowingTransaction>
        </postTransactionAmounts>
        <ownershipNature>
            <directOrIndirectOwnership>
                <value>D</value>
            </directOrIndirectOwnership>
        </ownershipNature>
    </nonDerivativeSecurity>

    <footnotes>
        <footnote id="F1">Stock Dividend</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Stewart C Adams Jr</signatureName>
        <signatureDate>2003-05-15</signatureDate>
    </ownerSignature>

</ownershipDocument>

