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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2016-05-06</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000074260</issuerCik>
        <issuerName>OLD REPUBLIC INTERNATIONAL CORP</issuerName>
        <issuerTradingSymbol>ORI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001584069</rptOwnerCik>
            <rptOwnerName>Smiddy Craig R</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>307 NORTH MICHIGAN AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 2300</rptOwnerStreet2>
            <rptOwnerCity>CHICAGO</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60601</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Exec.VP/CEO ORGeneral Ins.Cos.</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>2016 Employee Stock Option</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>18.14</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2016-05-06</value>
                <footnoteId id="F1"/>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>25000</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2016-05-06</value>
            </exerciseDate>
            <expirationDate>
                <value>2026-03-23</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>25000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>25000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Date of notice to the optionee.</footnote>
        <footnote id="F2">These shares vest and become exercisable each December 31 at the rate of 10% the first year, 15% the second year, 20% the third year, 25% the fourth year and 30% the fifth year. Also, vesting shall accelerate if the optionee dies, becomes disabled, retires or a change of control of the company occurs. For those optionees over age 65 and who have been employed for 10 years or more by the company on the date of grant, 100% of the option shares vest immediately.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>William J. Dasso, Power of Attorney for Craig R. Smiddy</signatureName>
        <signatureDate>2016-05-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
