<SEC-DOCUMENT>0001171843-26-001843.txt : 20260323
<SEC-HEADER>0001171843-26-001843.hdr.sgml : 20260323
<ACCEPTANCE-DATETIME>20260323094804
ACCESSION NUMBER:		0001171843-26-001843
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20260320
FILED AS OF DATE:		20260323
DATE AS OF CHANGE:		20260323

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Duke John D
		CENTRAL INDEX KEY:			0002071593
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-33957
		FILM NUMBER:		26780293

	MAIL ADDRESS:	
		STREET 1:		C/O HARVARD BIOSCIENCE, INC.
		STREET 2:		84 OCTOBER HILL ROAD
		CITY:			HOLLISTON
		STATE:			MA
		ZIP:			01746

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			HARVARD BIOSCIENCE INC
		CENTRAL INDEX KEY:			0001123494
		STANDARD INDUSTRIAL CLASSIFICATION:	LABORATORY ANALYTICAL INSTRUMENTS [3826]
		ORGANIZATION NAME:           	08 Industrial Applications and Services
		EIN:				043306140
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		84 OCTOBER HILL RD
		CITY:			HOLLISTON
		STATE:			MA
		ZIP:			01746
		BUSINESS PHONE:		5088938999

	MAIL ADDRESS:	
		STREET 1:		84 OCTOBER HILL ROAD
		CITY:			HOLLISTON
		STATE:			MA
		ZIP:			01746
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>ownership.xml
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0609</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2026-03-20</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001123494</issuerCik>
        <issuerName>HARVARD BIOSCIENCE INC</issuerName>
        <issuerTradingSymbol>HBIO</issuerTradingSymbol>
        <issuerForeignTradingSymbol></issuerForeignTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0002071593</rptOwnerCik>
            <rptOwnerName>Duke John D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>false</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>C/O HARVARD BIOSCIENCE, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>84 OCTOBER HILL ROAD</rptOwnerStreet2>
            <rptOwnerCity>HOLLISTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>01746</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Executive Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2026-03-20</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>75000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>180000</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">See remarks</footnote>
    </footnotes>

    <remarks>Includes (a) an award granting 75,000 restricted stock units (RSUs) that will vest in three equal installments on March 20, 2027, 2028, and 2029, subject to the terms set forth in an award agreement between the Issuer and the Reporting Person, (b) 5,000 shares of common stock purchased on March 16, 2026, (c) an award of 50,000 RSUs that will vest in three equal installments on August 8, 2026, 2027 and 2028, subject to the terms set forth in an award agreement between the Issuer and the Reporting Person and (d) an award of 50,000 RSUs with performance based vesting conditions. These RSUs will vest upon the achievement of a relative total shareholder return of the Issuer's common stock during the period from August 8, 2025 to the earlier of (i) July 30, 2028, and (ii) the date of a change of control, measured relative to the Russell2000 index, subject to the terms set forth in an award agreement between the Issuer and the Reporting Person. The target number of these RSUs that may be earned is reported above; the maximum amount is 150% of the number reported.</remarks>

    <ownerSignature>
        <signatureName>/s/ John D Duke</signatureName>
        <signatureDate>2026-03-23</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
