<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType>
<periodOfReport>2003-07-25</periodOfReport>
<notSubjectToSection16>0</notSubjectToSection16>
    <issuer>
        <issuerCik>0000831959</issuerCik>
        <issuerName>UNITED NATIONAL BANCORP</issuerName>
        <issuerTradingSymbol>UNBJ</issuerTradingSymbol>
</issuer>
<reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000922708</rptOwnerCik>
            <rptOwnerName>RUS ARLYN D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>913 SUNSET RIDGE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BRIDGEWATER</rptOwnerCity>
            <rptOwnerState>NJ</rptOwnerState>
            <rptOwnerZipCode>08807</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>1</isDirector>
<isOfficer>0</isOfficer>
<isTenPercentOwner>0</isTenPercentOwner>
<isOther>0</isOther>
</reportingOwnerRelationship>
</reportingOwner>
<derivativeTable>
<derivativeHolding>
<securityTitle>
<value>Non-Qualified Stock Option</value>
</securityTitle>
<conversionOrExercisePrice>
<value>29.08</value>
</conversionOrExercisePrice>
<exerciseDate>
<value>2007-07-25</value>
</exerciseDate>
<expirationDate>
<value>2013-07-25</value>
</expirationDate>
<underlyingSecurity>
<underlyingSecurityTitle>
<value>Common Stock</value>
</underlyingSecurityTitle>
<underlyingSecurityShares>
<value>3000</value>
</underlyingSecurityShares>
</underlyingSecurity>
<postTransactionAmounts>
<sharesOwnedFollowingTransaction>
<value>11496</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature>
<directOrIndirectOwnership>
<value>D</value>
</directOrIndirectOwnership>
</ownershipNature>
</derivativeHolding>
</derivativeTable>
<ownerSignature>
<signatureName>Arlyn D. Rus</signatureName>
<signatureDate>2003-07-29</signatureDate>
</ownerSignature>
</ownershipDocument>

