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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
 R7sLsLEXWqqKaTlNJnRaNW2QTiqrtVtWwuIJRa0vafIoExuLlPYHbaDcklCDrzLk
 BtSB9q7lKskQLWSKxl5aVA==

<SEC-DOCUMENT>0001104659-07-071784.txt : 20070927
<SEC-HEADER>0001104659-07-071784.hdr.sgml : 20070927
<ACCEPTANCE-DATETIME>20070927173848
ACCESSION NUMBER:		0001104659-07-071784
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20070925
FILED AS OF DATE:		20070927
DATE AS OF CHANGE:		20070927

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			AMAG PHARMACEUTICALS INC.
		CENTRAL INDEX KEY:			0000792977
		STANDARD INDUSTRIAL CLASSIFICATION:	IN VITRO & IN VIVO DIAGNOSTIC SUBSTANCES [2835]
		IRS NUMBER:				042742593
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0930

	BUSINESS ADDRESS:	
		STREET 1:		125 CAMBRIDGEPARK DRIVE, 6TH FLOOR
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02140
		BUSINESS PHONE:		6174972070

	MAIL ADDRESS:	
		STREET 1:		125 CAMBRIDGEPARK DRIVE, 6TH FLOOR
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02140

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ADVANCED MAGNETICS INC
		DATE OF NAME CHANGE:	19920703

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Pereira Brian JG
		CENTRAL INDEX KEY:			0001298146

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-14732
		FILM NUMBER:		071140198

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		617-497-2070

	MAIL ADDRESS:	
		STREET 1:		C/O ADVANCED MAGNETICS, INC.
		STREET 2:		61 MOONEY STREET
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02138
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>a4.xml
<DESCRIPTION>4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2007-09-25</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000792977</issuerCik>
        <issuerName>AMAG PHARMACEUTICALS INC.</issuerName>
        <issuerTradingSymbol>AMAG</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001298146</rptOwnerCik>
            <rptOwnerName>Pereira Brian JG</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O AMAG PHARMACEUTICALS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>125 CAMBRIDGEPARK DRIVE, 6TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>CAMBRIDGE</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02140</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President &amp; CEO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Employee Stock Options (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>54.97</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2007-09-25</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>45000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2017-09-25</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>45000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>45000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Grant of stock option pursuant to the AMAG Pharmaceuticals, Inc. Amended and Restated 2000 Stock Plan. This option is exercisable in four equal annual installments.  The first installment will vest on September 25, 2008, the first anniversary of the grant, and the next three installments will vest on September 25, 2009, September 25, 2010, and September 25, 2011.</footnote>
        <footnote id="F2">The exercise price is reported in column 2.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Joseph L. Farmer, attorney-in-fact</signatureName>
        <signatureDate>2007-09-27</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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