<SEC-DOCUMENT>0001125345-17-000047.txt : 20170502
<SEC-HEADER>0001125345-17-000047.hdr.sgml : 20170502
<ACCEPTANCE-DATETIME>20170502125829
ACCESSION NUMBER:		0001125345-17-000047
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20170428
FILED AS OF DATE:		20170502
DATE AS OF CHANGE:		20170502

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MACROGENICS INC
		CENTRAL INDEX KEY:			0001125345
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				000000000
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		9704 MEDICAL CENTER DRIVE
		CITY:			Rockville
		STATE:			MD
		ZIP:			20850
		BUSINESS PHONE:		301-251-5172

	MAIL ADDRESS:	
		STREET 1:		9704 MEDICAL CENTER DRIVE
		CITY:			ROCKVILLE
		STATE:			MD
		ZIP:			20850

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			SARAN ATUL
		CENTRAL INDEX KEY:			0001591070

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-36112
		FILM NUMBER:		17803998

	MAIL ADDRESS:	
		STREET 1:		C/O ZENCOR, INC.
		STREET 2:		111 WEST LEMON AVENUE
		CITY:			MONROVIA
		STATE:			CA
		ZIP:			91016
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_149374429435733.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2017-04-28</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001125345</issuerCik>
        <issuerName>MACROGENICS INC</issuerName>
        <issuerTradingSymbol>MGNX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001591070</rptOwnerCik>
            <rptOwnerName>SARAN ATUL</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>9704 MEDICAL CENTER DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>ROCKVILLE</rptOwnerCity>
            <rptOwnerState>MD</rptOwnerState>
            <rptOwnerZipCode>20850</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>SVP &amp; General Counsel</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2017-04-28</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1862</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>21.61</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>16986</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Represents shares of common stock withheld to pay taxes upon vesting of RSU originally granted to the Reporting Person on April 28, 2014. The number of shares withheld was determined on April 28, 2017 based on the closing price of the Company's common stock on that day.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/Lynn Cilinski, Attorney-in-Fact</signatureName>
        <signatureDate>2017-05-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
