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

         This certification is provided pursuant to Section 906 of the
Sarbanes-Oxley Act of 2002, 18 U.S.C. Section 1350, and accompanies the annual
report on Form 11-K for the year ended December 31, 2002 (the "Form 11-K") of
the Mercantile Bank of West Michigan 401(k) Plan (the "Issuer").

         I, Gerald R. Johnson, Jr., Trustee of the Issuer, certify that:

         (i)      the Form 11-K fully complies with the requirements of Section
                  13(a) or Section 15(d) of the Securities Exchange Act of 1934
                  (15 U.S.C. 78m(a) or 78o(d)); and

         (ii)     the information contained in the Form 11-K fairly presents, in
                  all material respects, the financial condition and results of
                  operations of the Issuer.

Dated: June 26, 2003

                                              /s/ Gerald R. Johnson, Jr.
                                              ----------------------------------
                                              Gerald R. Johnson, Jr.
                                              Trustee
                                              (chief executive officer)




         A signed original of this written statement required by Section 906 has
been provided to the Mercantile Bank of West Michigan 401(k) Plan and will be
retained by the Plan and furnished to the Securities and Exchange Commission or
its staff upon request.