-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 SSFO2eGcauGgzUbRof0wYA==

<SEC-DOCUMENT>0001374690-10-000003.txt : 20100301
<SEC-HEADER>0001374690-10-000003.hdr.sgml : 20100301
<ACCEPTANCE-DATETIME>20100301143854
ACCESSION NUMBER:		0001374690-10-000003
CONFORMED SUBMISSION TYPE:	D
PUBLIC DOCUMENT COUNT:		1
ITEM INFORMATION:		Rule 506
FILED AS OF DATE:		20100301
DATE AS OF CHANGE:		20100301
EFFECTIVENESS DATE:		20100301

FILER:

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ZAFGEN, INC.
		CENTRAL INDEX KEY:			0001374690
		IRS NUMBER:				203857670
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		D
		SEC ACT:		1933 Act
		SEC FILE NUMBER:	021-94401
		FILM NUMBER:		10643720

	BUSINESS ADDRESS:	
		STREET 1:		5 CAMBRIDGE CENTER, FLOOR 2
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02142
		BUSINESS PHONE:		(617 ) 864-1645

	MAIL ADDRESS:	
		STREET 1:		5 CAMBRIDGE CENTER, FLOOR 2
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02142

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ZAFGEN INC
		DATE OF NAME CHANGE:	20060906
</SEC-HEADER>
<DOCUMENT>
<TYPE>D
<SEQUENCE>1
<FILENAME>primary_doc.xml
<TEXT>
<XML>
<?xml version="1.0"?>
<edgarSubmission>

    <schemaVersion>X0603</schemaVersion>

    <submissionType>D</submissionType>

    <testOrLive>LIVE</testOrLive>

    <primaryIssuer>
        <cik>0001374690</cik>
        <entityName>ZAFGEN, INC.</entityName>
        <issuerAddress>
            <street1>5 CAMBRIDGE CENTER, FLOOR 2</street1>
            <city>CAMBRIDGE</city>
            <stateOrCountry>MA</stateOrCountry>
            <zipCode>02142</zipCode>
        </issuerAddress>
        <issuerPhoneNumber>(617 ) 864-1645</issuerPhoneNumber>
        <jurisdictionOfInc>DELAWARE</jurisdictionOfInc>
        <edgarPreviousNameList>
            <previousName>ZAFGEN INC</previousName>
        </edgarPreviousNameList>
        <entityType>Corporation</entityType>
        <yearOfInc>
            <withinFiveYears>true</withinFiveYears>
            <value>2005</value>
        </yearOfInc>
    </primaryIssuer>

    <relatedPersonsList>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Thomas</firstName>
                <lastName>Hughes</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>c/o Zafgen, Inc.</street1>
                <street2>5 Cambridge Center, Floor 2</street2>
                <city>Cambridge</city>
                <stateOrCountry>MA</stateOrCountry>
                <zipCode>02142</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification>CEO &amp; President</relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Matthias</firstName>
                <lastName>Jaffe</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>c/o Zafgen, Inc.</street1>
                <street2>5 Cambridge Center, Floor 2</street2>
                <city>Cambridge</city>
                <stateOrCountry>MA</stateOrCountry>
                <zipCode>02142</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification>CFO, Treasurer &amp; VP of Business Development</relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Mitchell</firstName>
                <middleName>S.</middleName>
                <lastName>Bloom</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>c/o Goodwin Procter LLP</street1>
                <street2>Exchange Place</street2>
                <city>Boston</city>
                <stateOrCountry>MA</stateOrCountry>
                <zipCode>02109</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification>Secretary</relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Peter</firstName>
                <lastName>Barrett</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>c/o Zafgen, Inc.</street1>
                <street2>5 Cambridge Center, Floor 2</street2>
                <city>Cambridge</city>
                <stateOrCountry>MA</stateOrCountry>
                <zipCode>02142</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Ari</firstName>
                <lastName>Goldberg</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>c/o Zafgen, Inc.</street1>
                <street2>5 Cambridge Center, Floor 2</street2>
                <city>Cambridge</city>
                <stateOrCountry>MA</stateOrCountry>
                <zipCode>02142</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Kevin</firstName>
                <lastName>Starr</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>c/o Zafgen, Inc.</street1>
                <street2>5 Cambridge Center, Floor 2</street2>
                <city>Cambridge</city>
                <stateOrCountry>MA</stateOrCountry>
                <zipCode>02142</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Bruce</firstName>
                <lastName>Booth</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>c/o Zafgen, Inc.</street1>
                <street2>5 Cambridge Center, Floor 2</street2>
                <city>Cambridge</city>
                <stateOrCountry>MA</stateOrCountry>
                <zipCode>02142</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Dr. Liam</firstName>
                <lastName>Ratcliffe</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>c/o Zafgen, Inc.</street1>
                <street2>5 Cambridge Center, Floor 2</street2>
                <city>Cambridge</city>
                <stateOrCountry>MA</stateOrCountry>
                <zipCode>02142</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Louis</firstName>
                <lastName>Tartaglia</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>c/o Zafgen, Inc.</street1>
                <street2>5 Cambridge Center, Floor 2</street2>
                <city>Cambridge</city>
                <stateOrCountry>MA</stateOrCountry>
                <zipCode>02142</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
    </relatedPersonsList>

    <offeringData>
        <industryGroup>
            <industryGroupType>Other Health Care</industryGroupType>
        </industryGroup>
        <issuerSize>
            <revenueRange>Decline to Disclose</revenueRange>
        </issuerSize>
        <federalExemptionsExclusions>
            <item>06</item>
        </federalExemptionsExclusions>
        <typeOfFiling>
            <newOrAmendment>
                <isAmendment>false</isAmendment>
            </newOrAmendment>
            <dateOfFirstSale>
                <value>2010-02-17</value>
            </dateOfFirstSale>
        </typeOfFiling>
        <durationOfOffering>
            <moreThanOneYear>true</moreThanOneYear>
        </durationOfOffering>
        <typesOfSecuritiesOffered>
            <isEquityType>true</isEquityType>
        </typesOfSecuritiesOffered>
        <businessCombinationTransaction>
            <isBusinessCombinationTransaction>false</isBusinessCombinationTransaction>
            <clarificationOfResponse></clarificationOfResponse>
        </businessCombinationTransaction>
        <minimumInvestmentAccepted>0</minimumInvestmentAccepted>
        <salesCompensationList></salesCompensationList>
        <offeringSalesAmounts>
            <totalOfferingAmount>10125000</totalOfferingAmount>
            <totalAmountSold>8100000</totalAmountSold>
            <totalRemaining>2025000</totalRemaining>
            <clarificationOfResponse></clarificationOfResponse>
        </offeringSalesAmounts>
        <investors>
            <hasNonAccreditedInvestors>false</hasNonAccreditedInvestors>
            <totalNumberAlreadyInvested>3</totalNumberAlreadyInvested>
        </investors>
        <salesCommissionsFindersFees>
            <salesCommissions>
                <dollarAmount>0</dollarAmount>
            </salesCommissions>
            <findersFees>
                <dollarAmount>0</dollarAmount>
            </findersFees>
            <clarificationOfResponse></clarificationOfResponse>
        </salesCommissionsFindersFees>
        <useOfProceeds>
            <grossProceedsUsed>
                <dollarAmount>0</dollarAmount>
            </grossProceedsUsed>
            <clarificationOfResponse></clarificationOfResponse>
        </useOfProceeds>
        <signatureBlock>
            <authorizedRepresentative>false</authorizedRepresentative>
            <signature>
                <issuerName>ZAFGEN, INC.</issuerName>
                <signatureName>Matthias Jaffe</signatureName>
                <nameOfSigner>Matthias Jaffe</nameOfSigner>
                <signatureTitle>CFO, Treasurer &amp; VP of Business Development</signatureTitle>
                <signatureDate>2010-03-01</signatureDate>
            </signature>
        </signatureBlock>
    </offeringData>
</edgarSubmission>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----