Exhibit 99.1

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 Natural Alternatives International, Inc. (the “Company”) on Form 10-Q for the period ending September 30, 2002 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), the undersigned, Mark A. LeDoux, Chief Executive Officer of the Company, and Randell Weaver, Chief Financial Officer of the Company, certify, pursuant to 18 U.S.C. § 1350, as adopted pursuant to § 906 of the Sarbanes-Oxley Act of 2002, that to our 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.

/s/    MARK A. LEDOUX                                                   

Mark A. LeDoux

Chief Executive Officer

November 13, 2002

/s/    RANDELL WEAVER                                                   

Randell Weaver

Chief Financial Officer

November 13, 2002