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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2008-08-04</periodOfReport>

    <dateOfOriginalSubmission>2008-08-04</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000723458</issuerCik>
        <issuerName>STATE BANCORP INC</issuerName>
        <issuerTradingSymbol>STBC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001411949</rptOwnerCik>
            <rptOwnerName>LaFalce John J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O HOGAN WILLIG</rptOwnerStreet1>
            <rptOwnerStreet2>ONE JAMES AUDUBON PKWY., STE. 210</rptOwnerStreet2>
            <rptOwnerCity>AMHERST</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>14228-1169</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>State Bancorp, Inc. Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-08-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>2898</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>12.9</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3000</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Joint with wife.</footnote>
        <footnote id="F2">Original purchase price was quoted as $11.85.  The correct purchase price should be $12.90.</footnote>
        <footnote id="F3">Original total amount of securities beneficially owned following reported transaction was quoted as 2,898.  The correct total is 3,000.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>John J. LaFalce</signatureName>
        <signatureDate>2008-08-20</signatureDate>
    </ownerSignature>
</ownershipDocument>
