-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
 MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen
 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 OQrIbkc3wAniD2JxtlRDVcxJ4LxItLzrBzuKHeskRDTzn28KreTOBt35hzlrL2Xk
 c/qL4oB0B+e4huN+7P/I3g==

<SEC-DOCUMENT>0001179110-08-017422.txt : 20080930
<SEC-HEADER>0001179110-08-017422.hdr.sgml : 20080930
<ACCEPTANCE-DATETIME>20080930132819
ACCESSION NUMBER:		0001179110-08-017422
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20080911
FILED AS OF DATE:		20080930
DATE AS OF CHANGE:		20080930

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Seiter Stephen Ridgely
		CENTRAL INDEX KEY:			0001432406

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-33888
		FILM NUMBER:		081096762

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		516-390-5300

	MAIL ADDRESS:	
		STREET 1:		C/O AMERICAN DEFENSE SYSTEMS, INC.
		STREET 2:		230 DUFFY AVENUE
		CITY:			HICKSVILLE
		STATE:			NY
		ZIP:			11801

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			AMERICAN DEFENSE SYSTEMS INC
		CENTRAL INDEX KEY:			0001260996
		STANDARD INDUSTRIAL CLASSIFICATION:	MISCELLANEOUS TRANSPORTATION EQUIPMENT [3790]
		IRS NUMBER:				000000000
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		230 DUFFY AVENUE
		CITY:			HICKSVILLE
		STATE:			NY
		ZIP:			11801
		BUSINESS PHONE:		516-390-5300

	MAIL ADDRESS:	
		STREET 1:		230 DUFFY AVENUE
		CITY:			HICKSVILLE
		STATE:			NY
		ZIP:			11801
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-09-11</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001260996</issuerCik>
        <issuerName>AMERICAN DEFENSE SYSTEMS INC</issuerName>
        <issuerTradingSymbol>EAG</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001432406</rptOwnerCik>
            <rptOwnerName>Seiter Stephen Ridgely</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O AMERICAN DEFENSE SYSTEMS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>230 DUFFY AVENUE</rptOwnerStreet2>
            <rptOwnerCity>HICKSVILLE</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>11801</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-09-11</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>5</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value>E</value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1450</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>.99</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2500</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes></footnotes>

    <ownerSignature>
        <signatureName>/s/Anya Coverman, attorney in fact</signatureName>
        <signatureDate>2008-09-30</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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