EXHIBIT 32.2



                            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 Annual Report of Westamerica Bancorporation (the
"Company") on Form 10-K for the period ending December 31, 2003 as filed with
the Securities and Exchange Commission on the date hereof (the "Report"), I,
Dennis R. Hansen, Principal Accounting Officer of the Company, certify, pursuant
to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the
Sarbanes-Oxley Act of 2002, that:

         (1) The Report fully complies with the requirements of section
         13(a)-14(b) or 15d-14(b) 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/  Dennis R. Hansen
- --------------------
Dennis R. Hansen
Senior Vice President, Controller and Principal Accounting Officer
March 8, 2004