1 EXHIBIT 5 DICKINSON, WRIGHT, MOON, VAN DUSEN & FREEMAN 500 WOODWARD AVENUE, SUITE 4000 DETROIT, MICHIGAN 48226-3425 TELEPHONE: (313) 223-3500 FACSIMILE: (313) 223-3598 August 5, 1997 Securities and Exchange Commission Judiciary Plaza 450 Fifth Street Washington, D.C. 20549 RE: MERCANTILE BANK CORPORATION Gentlemen: We are acting as counsel to Mercantile Bank Corporation, a Michigan corporation (the "Company") in connection with the proposed issuance and sale by the Company of shares of its common stock ("Common Stock"). The Common Stock is described in a registration statement on Form SB-2 (the "Registration Statement") filed by the Company with the Securities and Exchange Commission under the Securities Act of 1933, as amended (the "Act"). Based upon our examination of such corporate records and other documents and certificates as we deemed it necessary to examine, it is our opinion that: 1. The Company is a corporation validly existing under the laws of the State of Michigan; and 2. The Common Stock, when issued and sold by the Company, will be legally issued, fully paid and non-assessable. We hereby consent to the use of this opinion as Exhibit 5 to the Registration Statement and to the use of our firm name under the caption "Legal Matters" in the related Prospectus. In giving such consent, we do not concede that we are experts within the meaning of the Act or the rules or regulations thereunder or that this consent is required by Section 7 of the Act. Very truly yours, /s/ Dickinson, Wright, Moon, Van Dusen & Freeman