-----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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 DiVyCqqxbwXL5ovo8cvB4A==

<SEC-DOCUMENT>0001140361-07-003438.txt : 20070214
<SEC-HEADER>0001140361-07-003438.hdr.sgml : 20070214
<ACCEPTANCE-DATETIME>20070214140230
ACCESSION NUMBER:		0001140361-07-003438
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20070206
FILED AS OF DATE:		20070214
DATE AS OF CHANGE:		20070214

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			BRENNER LOUIS MD
		CENTRAL INDEX KEY:			0001389500

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-14732
		FILM NUMBER:		07617962

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		617-498-3300

	MAIL ADDRESS:	
		STREET 1:		C/O ADVANCED MAGNETICS, INC
		STREET 2:		125 CAMBRIDGEPARK DRIVE, 6TH FLOOR
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02140

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ADVANCED MAGNETICS 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
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 3
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2007-02-06</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000792977</issuerCik>
        <issuerName>ADVANCED MAGNETICS INC</issuerName>
        <issuerTradingSymbol>AMAG</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001389500</rptOwnerCik>
            <rptOwnerName>BRENNER LOUIS MD</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O ADVANCED MAGNETICS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>125 CAMBRIDGEPARK DRIVE, 6TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>CAMBRIDGE</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02140</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Senior Vice President</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>35.29</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2016-09-07</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>48000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">This option vests in four equal annual installments, with the first installment vesting on September 7, 2007.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Louis Brenner</signatureName>
        <signatureDate>2007-02-13</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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