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

    <schemaVersion>X0607</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2026-04-05</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000080661</issuerCik>
        <issuerName>PROGRESSIVE CORP/OH/</issuerName>
        <issuerTradingSymbol>PGR</issuerTradingSymbol>
        <issuerForeignTradingSymbol></issuerForeignTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0002123923</rptOwnerCik>
            <rptOwnerName>WITALEC DANIEL J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>false</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>300 NORTH COMMONS BLVD.</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MAYFIELD VILLAGE</rptOwnerCity>
            <rptOwnerState>OH</rptOwnerState>
            <rptOwnerZipCode>44143</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isOfficer>1</isOfficer>
            <officerTitle>Chief Strategy Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2449.926</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Restricted Stock Unit</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F3"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>4485.745</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Represents time-based restricted stock units granted to the reporting person by the issuer between 2022 and 2026 plus accrued dividend equivalents since the grant date. Subject to the terms of the applicable plan and award agreements, each award vests in three roughly equal installments in the third, fourth and fifth January following the date of grant, subject to earlier vesting or forfeiture in accordance with the plan and the award agreement. The following number of units are scheduled to vest on the following dates: 1/19/2027 - 1,452.959; 1/18/2028 - 1,114.255; 1/16/2029 - 961.281; 1/15/2030 - 611.25; and 1/21/2031 - 346.</footnote>
        <footnote id="F2">Expiration Date is the same as the Date Exercisable.</footnote>
        <footnote id="F3">Each Restricted Stock Unit represents a contingent right to receive one Common Share of the Company's stock.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Allyson L. Bach, By Power of Attorney</signatureName>
        <signatureDate>2026-04-07</signatureDate>
    </ownerSignature>
</ownershipDocument>
