<?xml version="1.0"?>

<ownershipDocument>

    <documentType>3</documentType>

    <periodOfReport>2003-07-07</periodOfReport>


    <noSecuritiesOwned>1</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000003673</issuerCik>
        <issuerName>ALLEGHENY ENERGY INC</issuerName>
        <issuerTradingSymbol>NYSE</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001222260</rptOwnerCik>
            <rptOwnerName>SERKES JEFFREY D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Senior Vice President &amp; CFO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>


    <ownerSignature>
        <signatureName>/S/ JEFFREY D. SERKES</signatureName>
        <signatureDate>2003-07-16</signatureDate>
    </ownerSignature>

</ownershipDocument>

