<SEC-DOCUMENT>0001808365-26-000004.txt : 20260608
<SEC-HEADER>0001808365-26-000004.hdr.sgml : 20260608
<ACCEPTANCE-DATETIME>20260608163612
ACCESSION NUMBER:		0001808365-26-000004
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20260604
FILED AS OF DATE:		20260608
DATE AS OF CHANGE:		20260608

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Knowles Julius
		CENTRAL INDEX KEY:			0001808365
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-39264
		FILM NUMBER:		261073180

	MAIL ADDRESS:	
		STREET 1:		MASS GENERAL BRIGHAM VENTURES
		STREET 2:		399 REVOLUTION DRIVE, SUITE 999
		CITY:			SOMERVILLE
		STATE:			MA
		ZIP:			02145

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Keros Therapeutics, Inc.
		CENTRAL INDEX KEY:			0001664710
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		ORGANIZATION NAME:           	03 Life Sciences
		EIN:				811173868
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		1050 WALTHAM STREET, SUITE 302
		CITY:			LEXINGTON
		STATE:			MA
		ZIP:			02421
		BUSINESS PHONE:		617-314-6297

	MAIL ADDRESS:	
		STREET 1:		1050 WALTHAM STREET, SUITE 302
		CITY:			LEXINGTON
		STATE:			MA
		ZIP:			02421
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>form4-06082026_080608.xml
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0609</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2026-06-04</periodOfReport>

    <issuer>
        <issuerCik>0001664710</issuerCik>
        <issuerName>Keros Therapeutics, Inc.</issuerName>
        <issuerTradingSymbol>KROS</issuerTradingSymbol>
        <issuerForeignTradingSymbol></issuerForeignTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001808365</rptOwnerCik>
            <rptOwnerName>Knowles Julius</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>false</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>C/O KEROS THERAPEUTICS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>1050 WALTHAM STREET, SUITE 302</rptOwnerStreet2>
            <rptOwnerCity>LEXINGTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02421</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>true</isDirector>
            <isOfficer>false</isOfficer>
            <isTenPercentOwner>false</isTenPercentOwner>
            <isOther>false</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>1</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2026-06-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>2625</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>10.73</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>10958</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>150047</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>102233</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F4"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The transactions were pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on December 5, 2025.</footnote>
        <footnote id="F2">The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $10.61 to $10.89 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.</footnote>
        <footnote id="F3">The securities are held by Partners Innovation Fund, LLC (&quot;PIF I&quot;). Partners Innovation Fund, LLC (&quot;Partners GP I&quot;) is the ultimate general partner of PIF I. The Reporting Person, a member of the board of directors of the Issuer, is a partner of Partners GP I and as a result, may be deemed to share voting and investment power with respect to the shares held by PIF I.</footnote>
        <footnote id="F4">The securities are held by Partners Innovation Fund II, L.P. (&quot;PIF II&quot;). Partners Innovation Fund II, LLC (&quot;Partners GP II&quot;) is the ultimate general partner of PIF II. The Reporting Person, a member of the board of directors of the Issuer, is a partner of Partners GP II and as a result, may be deemed to share voting and investment power with respect to the shares held by PIF II.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Keith Regnante, Attorney-in-Fact</signatureName>
        <signatureDate>2026-06-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
