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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 N25DzlqbJv7YmC2og3dUEWMO3C2LSkBVOcOfx3YdoOpKYTccGsilPgxssGIFYCvc
 R+Op9S2NtQQgsqwLv8Kg5g==

<SEC-DOCUMENT>0001140361-03-001938.txt : 20030609
<SEC-HEADER>0001140361-03-001938.hdr.sgml : 20030609
<ACCEPTANCE-DATETIME>20030609125059
ACCESSION NUMBER:		0001140361-03-001938
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20030605
FILED AS OF DATE:		20030609

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			ROTH DOUGLAS A
		CENTRAL INDEX KEY:			0001203044

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-04217
		FILM NUMBER:		03737040

	MAIL ADDRESS:	
		STREET 1:		9 KIMBERLY DR
		CITY:			E NORTHPORT
		STATE:			NY
		ZIP:			11731

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ACETO CORP
		CENTRAL INDEX KEY:			0000002034
		STANDARD INDUSTRIAL CLASSIFICATION:	WHOLESALE-CHEMICALS & ALLIED PRODUCTS [5160]
		IRS NUMBER:				111720520
		STATE OF INCORPORATION:			NY
		FISCAL YEAR END:			0630

	BUSINESS ADDRESS:	
		STREET 1:		ONE HOLLOW LANE
		CITY:			LAKE SUCCESS
		STATE:			NY
		ZIP:			11042
		BUSINESS PHONE:		5166276000

	MAIL ADDRESS:	
		STREET 1:		ONE HOLLOW LANE
		CITY:			LAKE SUCCESS
		STATE:			NY
		ZIP:			11042

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ACETO CHEMICAL CO INC
		DATE OF NAME CHANGE:	19851203
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0101</schemaVersion>

    <documentType>4</documentType>
<periodOfReport>2003-06-05</periodOfReport>
<notSubjectToSection16>0</notSubjectToSection16>
    <issuer>
        <issuerCik>0000002034</issuerCik>
        <issuerName>ACETO CORP</issuerName>
        <issuerTradingSymbol>ACET</issuerTradingSymbol>
</issuer>
<reportingOwner>
<reportingOwnerId>
            <rptOwnerCik>0001203044</rptOwnerCik>
            <rptOwnerName>ROTH DOUGLAS A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector>
<isOfficer>1</isOfficer>
<isTenPercentOwner>0</isTenPercentOwner>
<isOther>0</isOther>
<officerTitle>Chief Financial Officer</officerTitle>
<otherText></otherText>
</reportingOwnerRelationship>
</reportingOwner>
<nonDerivativeSecurity>
<securityTitle>
<value>Common Stock</value>
</securityTitle>
<transactionDate>
<value>2003-06-05</value>
</transactionDate>
<transactionCoding>
<transactionFormType>4</transactionFormType>
<transactionCode>A</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionTimeliness>
<value></value>
</transactionTimeliness>
<transactionAmounts>
<transactionShares>
<value>93</value>
</transactionShares>
<transactionValue>
<value>21.42</value>
</transactionValue>
<transactionAcquiredDisposedCode>
<value>A</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<postTransactionAmounts>
<sharesOwnedFollowingTransaction>
<value>1709</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature>
<directOrIndirectOwnership>
<value>D</value>
</directOrIndirectOwnership>
<natureOfOwnership>
<value></value>
</natureOfOwnership>
</ownershipNature>
</nonDerivativeSecurity>
<ownerSignature>
<signatureName>Douglas Roth</signatureName>
<signatureDate>2003-06-06</signatureDate>
</ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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