<SUBMISSION>
<ACCESSION-NUMBER>0001140361-08-022462
<TYPE>3
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20080922
<FILING-DATE>20081002
<DATE-OF-FILING-DATE-CHANGE>20081002
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>Schwaneke Jeffrey A.
<CIK>0001446919
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>3
<ACT>34
<FILE-NUMBER>001-31826
<FILM-NUMBER>081103944
</FILING-VALUES>
<BUSINESS-ADDRESS>
<PHONE>314-725-47477
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>7711 CARONDELET
<CITY>ST. LOUIS
<STATE>MO
<ZIP>63105
</MAIL-ADDRESS>
</REPORTING-OWNER>
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>CENTENE CORP
<CIK>0001071739
<ASSIGNED-SIC>6324
<IRS-NUMBER>041406317
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>7711 CARONDELET AVE
<CITY>ST LOUIS
<STATE>MO
<ZIP>63105
<PHONE>3147254477
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>7711 CARONDELET AVE
<STREET2>SUITE 800
<CITY>ST LOUIS
<STATE>MO
<ZIP>63105
</MAIL-ADDRESS>
</ISSUER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 3
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0203</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2008-09-22</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001071739</issuerCik>
        <issuerName>CENTENE CORP</issuerName>
        <issuerTradingSymbol>CNC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001446919</rptOwnerCik>
            <rptOwnerName>Schwaneke Jeffrey A.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>7711 CARONDELET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>ST. LOUIS</rptOwnerCity>
            <rptOwnerState>MO</rptOwnerState>
            <rptOwnerZipCode>63105</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>VP, Cont. &amp; Chief Acct Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5000</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Common Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>17.38</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2013-07-07</value>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2018-07-07</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>15000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Mr. Schwaneke's ownership includes a previous award of 5,000 restricted stock units which vest in five equal annual installments on the anniversary of the grant date beginning on July 7, 2009.</footnote>
        <footnote id="F2">The options vest in five equal annual installments on the anniversary of the grant date, with the final vesting taking place on the date exercisable.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Jeffrey A. Schwaneke</signatureName>
        <signatureDate>2008-10-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
