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

    <schemaVersion>X0203</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2009-10-05</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000867665</issuerCik>
        <issuerName>ABRAXAS PETROLEUM CORP</issuerName>
        <issuerTradingSymbol>AXAS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001473980</rptOwnerCik>
            <rptOwnerName>Melton Brian L</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>18803 MEISNER DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAN ANTONIO</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>78258</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Abraxas Petroleum Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>17000</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Revieved in exchange for 4000 restricted units of Abraxas Energy Partners, L.P. in connection with the merger of Abraxas Energy Partners, L.P. into Abraxas Merger Sub, LLC, a wholly owned subsidiary of Abraxas Petroleum Corporation (the &quot;Merger&quot;). On the effective date of the Merger, the closing price of Abraxas Petroleum Corporation's common stock was $1.75.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Brian L. Melton</signatureName>
        <signatureDate>2009-10-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
