Exhibit 32.1

AMERICAN VANGUARD CORPORATION

CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350 AS ADOPTED

PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of American Vanguard Corporation (the “Company”) on Form 10-Q for the period ended June 30, 2004 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), the undersigned Chief Executive Officer and Chief Financial Officer of the Company hereby certify, pursuant to 18 U.S.C. §1350, as adopted pursuant to §906 of the Sarbanes-Oxley Act of 2002 that, based on their knowledge: (1) the Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934, and (2) the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company as of and for the periods covered in the Report.

/s/    ERIC G. WINTEMUTE        

Eric G. Wintemute,

Chief Executive Officer

/s/    JAMES A. BARRY        

James A. Barry,

Chief Financial Officer

August 13, 2004

A signed original of this written statement required by Section 906, or other document authenticating, acknowledging, or otherwise adopting the signature that appears in typed form within the electronic version of this written statement required by Section 906, has been provided to American Vanguard Corporation and will be retained by American Vanguard Corporation and furnished to the Securities and Exchange Commission or its staff upon request.

This certification set forth above is being furnished as an exhibit solely pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 and is not being filed as part of the Form 10-Q or as a separate document of the Company or the certifying officers.