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                                                                       EXHIBIT 5



                                 June 5, 2001




Securities and Exchange Commission
450 Fifth Street, N.W.
Washington, D.C.  20549

          Re:  American Pacific Corporation -
               Registration Statement on Form S-8 filed June 7, 2001
               -----------------------------------------------------

Dear Sir or Madam:

          We are counsel to American Pacific Corporation ("Registrant"). We
furnish this opinion in connection with the above-referenced Registration
Statement relating to 350,000 shares of Common Stock of the Registrant (the
"Securities") issuable upon the exercise of stock options granted or to be
granted under the Registrant's 2001 Stock Option Plan (the "Options").

          In furnishing our opinion, we have examined the Certificate of
Incorporation and the By-Laws of the Registrant, and such other instruments and
documents, including the minutes of the meetings of the Board of Directors of
Registrant, as well as certificates of public officials and officers of the
Registrant, as we have deemed relevant and necessary as the basis for our
opinion expressed herein. We have examined originals or certified, conformed or
photostatic copies of all documents, the authenticity of which has been
established to our satisfaction. In all such examinations, we have assumed the
genuineness of all signatures on original and certified documents, and the
conformity to executed documents of all unexecuted copies submitted to us as
conformed or photostatic copies.

          Based upon the foregoing, we are of the opinion that the Securities
have been duly authorized and will be legally issued, fully paid and
non-assessable; subject, however, to receipt by the Registrant of the exercise
price for the Options.

          We hereby consent to use of this opinion in the Registration
Statement.

          We advise you that Victor M. Rosenzweig, a member of our firm, is a
director of the Registrant and holds shares, and options to purchase shares, of
the Registrant's Common Stock.

                                 Very truly yours,



                                 OLSHAN GRUNDMAN FROME ROSENZWEIG & WOLOSKY LLP
