Exhibit 5.1

                               LEHMAN & EILEN LLP
                           50 Charles Lindbergh Blvd.
                                    Suite 505
                               Uniondale, NY 11553
                                  (516)222-0888

                                                        November 20, 2003

The Board of Directors
Aceto Corporation
One Hollow Lane
Lake Success, NY 11042

                  Re:      Registration Statement on Form S-8

Gentlemen:

         We are counsel to Aceto Corporation, a New York Corporation (the
"Company"), in connection with the filing by the Company with the Unites States
Securities and Exchange Commission pursuant to the Securities Act of 1933, as
amended (the "Securities Act"), of a registration statement on Form S-8 (the
"Registration Statement") relating to 500,000 shares (the "Shares") of the
Company's common stock, par value $.01, issuable upon the exercise of options
granted pursuant to the Company's 2002 Stock Option Plan (the "2002 Plan").

         We have examined and are familiar with originals or copies, certified
or otherwise identified to our satisfaction, of the Certificate of Incorporation
and By-Laws of the Company, as each is currently in effect, the Registration
Statement, the 2002 Plan, resolutions of the Board of Directors of the Company
relating to the adoption of the 2002 Plan and the proposed registration and
issuance of the Shares and such other corporate documents and records and other
certificates, and we have made such investigations of law as we have deemed
necessary or appropriate in order to render the opinions hereinafter set forth.

         In our examination, we have assumed the genuineness of all signatures,
the legal capacity of all natural persons, the authenticity of all documents
submitted to us as originals, the conformity to original documents of all
documents submitted to us as certified or photostatic copies and the
authenticity of the originals of such latter documents. As to any facts material
to the opinions expressed herein which were not independently established or
verified, we have relied upon statements and representations of officers and
other representatives of the Company and others.

         Based upon and subject to the foregoing, we are of the opinion that the
Shares to be issued upon exercise of any options duly granted pursuant to the
terms of the 2002 Plan have been duly and validly authorized and, when the
Shares have been paid for in accordance with the terms of the 2002 Plan, such
Shares will be duly and validly issued, fully paid and non-assessable.

         We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement. In giving this consent, we do not hereby admit that we
are within the category of persons whose consent is required under Section 7 of
the Securities Act, or the rules and regulations of the Securities and Exchange
Commission thereunder.

                                                        Very truly yours,

                                                        LEHMAN & EILEN LLP

                                                        By: /s/ Hank Gracin
                                                            ---------------
                                                            Hank Gracin, Partner