-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 T1ozuPXp84QmIk+MUuOWqLdV6HN0Cva7SJRjfsGyKnBr04Me7tIktrPR+mBe66UN
 nanU88vJJ1rd9tWI8PxuGw==

<SEC-DOCUMENT>0001317757-09-000012.txt : 20090609
<SEC-HEADER>0001317757-09-000012.hdr.sgml : 20090609
<ACCEPTANCE-DATETIME>20090609102110
ACCESSION NUMBER:		0001317757-09-000012
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20090608
FILED AS OF DATE:		20090609
DATE AS OF CHANGE:		20090609

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Zayas Ricardo
		CENTRAL INDEX KEY:			0001465314

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-14732
		FILM NUMBER:		09881094

	MAIL ADDRESS:	
		STREET 1:		100 HAYDEN AVENUE
		CITY:			LEXINGTON
		STATE:			MA
		ZIP:			02421

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:			1231

	BUSINESS ADDRESS:	
		STREET 1:		100 HAYDEN AVENUE
		CITY:			LEXINGTON
		STATE:			MA
		ZIP:			02140
		BUSINESS PHONE:		6174972070

	MAIL ADDRESS:	
		STREET 1:		100 HAYDEN AVENUE
		CITY:			LEXINGTON
		STATE:			MA
		ZIP:			02140

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ADVANCED MAGNETICS INC
		DATE OF NAME CHANGE:	19920703
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-06-08</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001465314</rptOwnerCik>
            <rptOwnerName>Zayas Ricardo</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>100 HAYDEN AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>LEXINGTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02421</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Sr. Vice President, Operations</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Employee Stock Options</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>53.1</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2009-06-08</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>50000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2019-06-08</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>50000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>50000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Restricted Stock Unit</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F3"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2009-06-08</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>10000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F4"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>10000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>10000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Exercisable in four equal installments. The first installment will vest on June 8, 2010, the first anniversary of the date of grant. The remaining three installments will vest on June 8, 2011, June 8, 2012 and June 8, 2013, respectively.</footnote>
        <footnote id="F2">Price is not applicable.</footnote>
        <footnote id="F3">Price is not applicable.</footnote>
        <footnote id="F4">Not applicable.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/Joseph L. Farmer, attorney-in-fact</signatureName>
        <signatureDate>2009-06-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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