<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>3</documentType>
<periodOfReport>2003-12-10</periodOfReport>
    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001123333</issuerCik>
        <issuerName>SPECIALTY LABORATORIES INC</issuerName>
        <issuerTradingSymbol>sp</issuerTradingSymbol>
</issuer>
<reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001274021</rptOwnerCik>
            <rptOwnerName>SADRI MARYAM</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2211 MICHIGAN AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SANTA MONICA</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>90404-3900</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector>
<isOfficer>1</isOfficer>
<isTenPercentOwner>0</isTenPercentOwner>
<isOther>0</isOther>
<officerTitle>VP, Laboratory Operations</officerTitle>
<otherText></otherText>
</reportingOwnerRelationship>
</reportingOwner>
<nonDerivativeTable></nonDerivativeTable>
<derivativeTable><derivativeHolding><securityTitle><value>Stock Option (Right to buy)</value>
</securityTitle>
<conversionOrExercisePrice><value>1.56</value>
</conversionOrExercisePrice>
<exerciseDate><value>2001-01-01</value>
</exerciseDate>
<expirationDate><value>2010-01-01</value>
</expirationDate>
<underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value>
</underlyingSecurityTitle>
<underlyingSecurityShares><value>11000</value>
</underlyingSecurityShares>
</underlyingSecurity>
<ownershipNature><directOrIndirectOwnership><value>D</value>
</directOrIndirectOwnership>
</ownershipNature>
</derivativeHolding>
<derivativeHolding><securityTitle><value>Stock Option (Right to buy)</value>
</securityTitle>
<conversionOrExercisePrice><value>23.00</value>
</conversionOrExercisePrice>
<exerciseDate><value>2003-02-08</value>
</exerciseDate>
<expirationDate><value>2012-02-08</value>
</expirationDate>
<underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value>
</underlyingSecurityTitle>
<underlyingSecurityShares><value>3500</value>
</underlyingSecurityShares>
</underlyingSecurity>
<ownershipNature><directOrIndirectOwnership><value>D</value>
</directOrIndirectOwnership>
</ownershipNature>
</derivativeHolding>
<derivativeHolding><securityTitle><value>Stock Option (Right to buy)</value>
</securityTitle>
<conversionOrExercisePrice><value>8.06</value>
</conversionOrExercisePrice>
<exerciseDate><value>2003-05-09</value>
</exerciseDate>
<expirationDate><value>2012-05-09</value>
</expirationDate>
<underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value>
</underlyingSecurityTitle>
<underlyingSecurityShares><value>5000</value>
</underlyingSecurityShares>
</underlyingSecurity>
<ownershipNature><directOrIndirectOwnership><value>D</value>
</directOrIndirectOwnership>
</ownershipNature>
</derivativeHolding>
<derivativeHolding><securityTitle><value>Stock Option (Right to buy)</value>
</securityTitle>
<conversionOrExercisePrice><value>7.22</value>
</conversionOrExercisePrice>
<exerciseDate><value>2004-02-14</value>
</exerciseDate>
<expirationDate><value>2013-02-14</value>
</expirationDate>
<underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value>
</underlyingSecurityTitle>
<underlyingSecurityShares><value>7500</value>
</underlyingSecurityShares>
</underlyingSecurity>
<ownershipNature><directOrIndirectOwnership><value>D</value>
</directOrIndirectOwnership>
</ownershipNature>
</derivativeHolding>
<derivativeHolding><securityTitle><value>Stock Option (Right to buy)</value>
</securityTitle>
<conversionOrExercisePrice><value>13.18</value>
</conversionOrExercisePrice>
<exerciseDate><value>2004-09-22</value>
</exerciseDate>
<expirationDate><value>2013-09-22</value>
</expirationDate>
<underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value>
</underlyingSecurityTitle>
<underlyingSecurityShares><value>30000</value>
</underlyingSecurityShares>
</underlyingSecurity>
<ownershipNature><directOrIndirectOwnership><value>D</value>
</directOrIndirectOwnership>
</ownershipNature>
</derivativeHolding>
</derivativeTable>
<footnotes></footnotes>
<ownerSignature><signatureName>Maryam Sadri by Les McClafferty-Helley, Attorney in Fact</signatureName>
<signatureDate>2003-12-19</signatureDate>
</ownerSignature>
</ownershipDocument>

