<ownershipDocument>
    <schemaVersion>X0101</schemaVersion>

    <documentType>3</documentType>
<periodOfReport>2003-07-03</periodOfReport>
    <noSecuritiesOwned>1</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001123333</issuerCik>
        <issuerName>SPECIALTY LABORATORIES INC</issuerName>
        <issuerTradingSymbol>sp</issuerTradingSymbol>
</issuer>
<reportingOwner><reportingOwnerId>
            <rptOwnerCik>0001251862</rptOwnerCik>
            <rptOwnerName>FRENCH CYNTHIA K</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector>
<isOfficer>1</isOfficer>
<isTenPercentOwner>0</isTenPercentOwner>
<isOther>0</isOther>
<officerTitle>VP, Chief Science Officer</officerTitle>
<otherText></otherText>
</reportingOwnerRelationship>
</reportingOwner>
<footnotes></footnotes>
<ownerSignature><signatureName>Cynthia K. French</signatureName>
<signatureDate>2003-07-03</signatureDate>
</ownerSignature>
</ownershipDocument>

