<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0101</schemaVersion>

    <documentType>4</documentType><periodOfReport>2003-05-15</periodOfReport>
    <issuer>
        <issuerCik>0000707605</issuerCik>
        <issuerName>AMERISERV FINANCIAL INC /PA/</issuerName>
        <issuerTradingSymbol>ASRV</issuerTradingSymbol></issuer><reportingOwner><reportingOwnerId>
            <rptOwnerCik>0001180674</rptOwnerCik>
            <rptOwnerName>CERNIC EDWARD J SR</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>1</isDirector><isOfficer>0</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther></reportingOwnerRelationship></reportingOwner><nonDerivativeSecurity><securityTitle><value>Common</value></securityTitle><transactionDate><value>2003-05-15</value></transactionDate><deemedExecutionDate><value>2003-05-20</value></deemedExecutionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>P</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>466.563</value></transactionShares><transactionValue><value>3.215</value></transactionValue><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>67445.9024</value><footnoteId id="F1"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></nonDerivativeSecurity><footnotes><footnote id="F1">Recap:  Form 4 filed 4/30/03    66,979.3394 +466.5630 shares Transaction reported above = 67,445.9024 shares. </footnote></footnotes><ownerSignature><signatureName>Betty L. Jakell, Attorney-in-Fact</signatureName><signatureDate>2003-05-21</signatureDate></ownerSignature></ownershipDocument>

