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

    <schemaVersion>X0607</schemaVersion>

    <documentType>3/A</documentType>

    <periodOfReport>2026-03-18</periodOfReport>

    <dateOfOriginalSubmission>2026-03-18</dateOfOriginalSubmission>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001341170</issuerCik>
        <issuerName>EUROSEAS LTD.</issuerName>
        <issuerTradingSymbol>ESEA</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0002122342</rptOwnerCik>
            <rptOwnerName>Pariaros Symeon</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>true</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>4 MESSOGEIOU &amp; EVROPIS STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MAROUSSI</rptOwnerCity>
            <rptOwnerNonUSStateTerritory></rptOwnerNonUSStateTerritory>
            <rptOwnerCountry>J3</rptOwnerCountry>
            <rptOwnerZipCode>151 24</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Administrative Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common stock</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2850</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Represents 2,850 shares of unvested incentive stock awards, of which 950 will vest on July 1, 2026, 950 shares will vest on November 13,2026 and 950 shares will vest on July 1, 2027.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Symeon Pariaros</signatureName>
        <signatureDate>2026-03-19</signatureDate>
    </ownerSignature>
</ownershipDocument>
