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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2015-03-20</periodOfReport>

    <dateOfOriginalSubmission>2015-03-24</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000790202</issuerCik>
        <issuerName>FIRST OPPORTUNITY FUND INC</issuerName>
        <issuerTradingSymbol>FOFI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001245548</rptOwnerCik>
            <rptOwnerName>MURPHEY NICOLE L</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2344 SPRUCE STREET</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE A</rptOwnerStreet2>
            <rptOwnerCity>BOULDER</rptOwnerCity>
            <rptOwnerState>CO</rptOwnerState>
            <rptOwnerZipCode>80302</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Treasurer, V.P &amp; CFO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2015-03-20</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>425</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">On March 20, 2015, Boulder Total Return Fund, Inc. (&quot;BTF&quot;), The Denali Fund Inc. (&quot;DNY&quot;) and First Opportunity Fund, Inc. (&quot;FOFI&quot;) reorganized into Boulder Growth &amp; Income Fund, Inc. (&quot;BIF&quot;) (the &quot;Reorganization&quot;) pursuant to that certain Agreement and Plan of Reorganization, dated as of March 5, 2015 (the &quot;Agreement&quot;).  Pursuant to the Agreement, BIF acquired all of the assets and liabilities of BTF, DNY and FOFI in exchange for common shares of BIF (the &quot;BIF Shares&quot;).</footnote>
        <footnote id="F2">The Reorganization occurred based on the relative net asset values (&quot;NAV&quot;) of BIF, BTF, DNY and FOFI as of the close of regular trading on the New York Stock Exchange on March 20, 2015. At such time, BIF reported net assets of $273,608,352.67 and a NAV per share of $10.73 and FOFI reported net assets of $342,875,845.30 and a NAV per share of $11.93. Holders of FOFI shares received 1.111719 BIF Shares for each FOFI share owned. Fractional shares were paid in cash.</footnote>
        <footnote id="F3">In connection with the Reorganization, Nicole L. Murphey received 472 BIF Shares (and cash for fractional shares, if any) for her 425 shares of FOFI.</footnote>
    </footnotes>

    <remarks>This Form 4/A (this &quot;Amendment&quot;) is being filed by the Reporting Person to amend and restate in its entirety the Form 4 originally filed by the Reporting Person with the Securities and Exchange Commission on March 24, 2015 (the &quot;Original Form 4&quot;).  This Amendment revises the Original Form 4 by (i) correcting the transaction code in Column 3 of Table I to reflect that the disposition of shares was an exempt transaction under Rule 16b-3(e) and not an open market or private sale of non-derivative or derivative security and (ii) amending the footnotes to provide more adequate disclosure of the Reorganization.</remarks>

    <ownerSignature>
        <signatureName>/s/ Nicole L. Murphey</signatureName>
        <signatureDate>2015-05-07</signatureDate>
    </ownerSignature>
</ownershipDocument>
