<SUBMISSION>
<ACCESSION-NUMBER>0001104659-08-040939
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20080617
<FILING-DATE>20080619
<DATE-OF-FILING-DATE-CHANGE>20080619
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>Fifth Street Finance Corp
<CIK>0001414932
<IRS-NUMBER>261219283
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>0930
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>WHITE PLAINS PLAZA
<STREET2>445 HAMILTON AVENUE, SUITE 1206
<CITY>WHITE PLAINS
<STATE>NY
<ZIP>10601
<PHONE>(914) 286-6800
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>WHITE PLAINS PLAZA
<STREET2>445 HAMILTON AVENUE, SUITE 1206
<CITY>WHITE PLAINS
<STATE>NY
<ZIP>10601
</MAIL-ADDRESS>
</ISSUER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>Berkman Adam C
<CIK>0001420005
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>814-00755
<FILM-NUMBER>08907811
</FILING-VALUES>
<BUSINESS-ADDRESS>
<PHONE>914-286-6800
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>WHITE PLAINS PLAZA
<STREET2>445 HAMILTON AVENUE, SUITE 1206
<CITY>WHITE PLAINS
<STATE>NY
<ZIP>10601
</MAIL-ADDRESS>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>a4.xml
<DESCRIPTION>4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-06-17</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001414932</issuerCik>
        <issuerName>Fifth Street Finance Corp</issuerName>
        <issuerTradingSymbol>FSC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001420005</rptOwnerCik>
            <rptOwnerName>Berkman Adam C</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>445 HAMILTON AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 1206</rptOwnerStreet2>
            <rptOwnerCity>WHITE PLAINS</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10601</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-06-17</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>14.12</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <ownerSignature>
        <signatureName>/s/ Bernard D. Berman (attorney-in-fact for Adam C. Berkman)</signatureName>
        <signatureDate>2008-06-19</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
