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

    <documentType>4</documentType><periodOfReport>2003-06-26</periodOfReport>
    <issuer>
        <issuerCik>0000354869</issuerCik>
        <issuerName>FIRSTMERIT CORP /OH/</issuerName>
        <issuerTradingSymbol>FMER</issuerTradingSymbol></issuer><reportingOwner><reportingOwnerId>
            <rptOwnerCik>0001231621</rptOwnerCik>
            <rptOwnerName>BLICKLE JOHN C</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><officerTitle></officerTitle><otherText></otherText></reportingOwnerRelationship></reportingOwner><nonDerivativeSecurity><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2003-06-16</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>J</transactionCode><equitySwapInvolved>0</equitySwapInvolved><footnoteId id="F1" /></transactionCoding><transactionTimeliness><value></value></transactionTimeliness><transactionAmounts><transactionShares><value>363.23</value></transactionShares><transactionValue><value>23.95</value></transactionValue><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>35160.5329</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>by Managed Account</value></natureOfOwnership></ownershipNature></nonDerivativeSecurity><nonDerivativeSecurity><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2003-06-26</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>J</transactionCode><equitySwapInvolved>0</equitySwapInvolved><footnoteId id="F4" /></transactionCoding><transactionTimeliness><value></value></transactionTimeliness><transactionAmounts><transactionShares><value>207.886</value></transactionShares><transactionValue><value>23.25</value></transactionValue><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>35368.42</value><footnoteId id="F2" /></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>by Managed Account</value><footnoteId id="F3" /></natureOfOwnership></ownershipNature></nonDerivativeSecurity><footnotes><footnote id="F1">Allocated to the reporting person's account pursuant to a dividend reinvestment feature of the FirstMerit Corporation Director Deferred Compensation Plan.</footnote><footnote id="F2">Reporting person also holds 27,260.00 directly, 2,152.00 indirectly, by spouse and 1,100.00 by a related corporation.</footnote><footnote id="F3">Shares in reporting person's account under FirstMerit Corporation Director Deferred Compensation Plan.</footnote><footnote id="F4">Allocated to the reporting person's account under FirstMerit Corporation Director Deferred Compensation Plan.</footnote></footnotes><ownerSignature><signatureName>By:  Terry E. Patton
For: John C. Blickle</signatureName><signatureDate>2003-06-27</signatureDate></ownerSignature></ownershipDocument>

