<DOCUMENT>
<TYPE>EX-5.1
<SEQUENCE>2
<FILENAME>a73775orex5-1.txt
<DESCRIPTION>EXHIBIT 5.1
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<PAGE>   1


                                                                     EXHIBIT 5.1


                      [McDermott, Will & Emery Letterhead]

June 28, 2001


Board of Directors
American Vanguard Corporation
4695 MacArthur Court, Suite 1250
Newport Beach, California 92660

        RE: Registration Statement on Form S-8

Gentlemen:

        We have acted as counsel for American Vanguard Corporation (the
"Company") in connection with the preparation and filing of a Registration
Statement on Form S-8 (the "Registration Statement") for the registration under
the Securities Act of 1933, as amended, of 200,000 shares of the Company's
Common Stock, par value $.10 per share (the "Common Stock"), which may be issued
pursuant to the Company's Employee Stock Purchase Plan (the "Plan").

        We have examined or considered:

        1. A copy of the Company's Certificate of Incorporation, as amended;

        2. A copy of the Company's Bylaws, as amended;

        3. Copies of resolutions duly adopted by the Board of Directors of the
           Company adopting the Plan; and

        4. A copy of the Plan.

        In addition to the examination outlined above, we have reviewed such
additional matters and have ascertained or verified, to our satisfaction, such
additional facts as we deemed necessary or appropriate for the purposes of this
opinion.

        We are of the opinion that the Common Stock, when issued pursuant to and
in accordance with the terms of the Plan against payment of the purchase price
provided for therein, will be legally issued, fully paid and nonassessable.

        We hereby consent to the reference to our firm in the Registration
Statement and to the filing of this opinion by the Company as an Exhibit to the
Registration Statement.


                                                Yours very truly,


                                                /s/ McDermott, Will & Emery


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