<PAGE>   1
                                                          Registration No. 333--

                     U.S. SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      Under
                           The Securities Act of 1933

                             -----------------------

                           MERCANTILE BANK CORPORATION
              (Exact number of issuer as specified in its charter)

        Michigan                                      38-3360865
(State or other jurisdiction of             (I.R.S. Employer Identification No.)
of incorporation or organization)

             216 North Division Avenue, Grand Rapids, Michigan 49503
               (Address of Principal Executive Offices) (Zip Code)

                  MERCANTILE BANK OF WEST MICHIGAN 401(K) PLAN
                            (Full title of the plan)

                        GERALD R. JOHNSON, JR., CHAIRMAN
                           Mercantile Bank Corporation
                            216 North Division Avenue
                          Grand Rapids, Michigan 49503
                     (Name and Address of Agent for service)
          Telephone number, including area code, of agent for service:
                                 (616) 242-9000

                          COPIES OF COMMUNICATIONS TO:
                               JEROME M. SCHWARTZ
                              Dickinson Wright PLLC
                         500 Woodward Avenue, Suite 4000
                             Detroit, Michigan 48226

                  Approximate date of proposed public offering:
 As soon as practicable after the effective date of this Registration Statement

                         CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>

-------------------------------- ---------------------- ------------------------- ------------------------ -----------------
                                                            Proposed Maximum             Proposed
      Title of Securities            Amount to be           Offering Price Per       Maximum Aggregate        Amount of
       to be Registered*              Registered                Share**              Offering Price**      Registration Fee
-------------------------------- ---------------------- ------------------------- ------------------------ -----------------
<S>                                  <C>                         <C>                     <C>                     <C> 
         Common Stock                50,000 Shares               $14.00                  $700,000                $195
-------------------------------- ---------------------- ------------------------- ------------------------ -----------------
</TABLE>

*In addition, pursuant to Rule 416(c) under the Securities Act of 1933, this
registration statement also covers an indeterminate amount of interests to be
offered or sold pursuant to the employee benefit plan described herein.
**Based upon the average of the bid and ask prices on March 30, 1999



<PAGE>   2




                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

         Mercantile Bank Corporation (the "Company") and the Mercantile Bank of
West Michigan 401(k) Plan (the "Plan") hereby incorporate by reference in this
Registration Statement the following document previously filed with the
Securities and Exchange Commission (the "Commission") under the Securities
Exchange Act of 1934, as amended (the "Exchange Act"):

         1. The Company's Annual Report on Form 10-KSB for the year ended
December 31, 1998.

         All documents subsequently filed with the Commission by the Company or
the Plan pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act
prior to the filing of a post-effective amendment which indicates that all
securities offered hereby have been sold or which deregisters all securities
then remaining unsold shall be deemed to be incorporated herein by reference and
to be a part hereof from the dates of filing of such documents.

ITEM 4.  DESCRIPTION OF SECURITIES

         The Company's authorized capital stock consists of 9,000,000 shares of
Common Stock and 1,000,000 shares of Preferred Stock. As of the date of this
Registration Statement, there are 2,472,500 shares of Common Stock issued and
outstanding. No shares of Preferred Stock have been issued by the Company.

         Michigan law allows the Company's Board of Directors to issue
additional shares of stock up to the total amount of Common Stock and Preferred
Stock authorized without obtaining the prior approval of the shareholders.

PREFERRED STOCK

         The Board of Directors of the Company is authorized to issue Preferred
Stock, in one or more series, from time to time, with such voting powers, full
or limited but not to exceed one vote per share, or without voting powers, and
with such designations, preferences and relative, participating, optional or
other special rights, and qualifications, limitation or restrictions thereof, as
may be provided in the resolution or resolutions adopted by the Board of
Directors. The authority of the Board of Directors includes, but is not limited
to, the determination or fixing of the following with respect to shares of such
class or any series thereof: (i) the number of shares and designation of such
series; (ii) the dividend rate and whether dividends are to be cumulative; (iii)
whether shares are to be redeemable, and, if so, whether redeemable for cash,
property or rights; (iv) the rights to which the holders of shares shall be
entitled, and the preferences, if any, over any other series; (v) whether the
shares shall be subject to the operation of a purchase, retirement or sinking
fund, and, if so, upon what conditions; (vi) whether the shares shall be
convertible into or exchangeable for shares of any other class or of any other
series of any class of capital stock and the terms and conditions of such
conversion or exchange; (vii) the voting powers, full or limited, if any, of the
shares; (viii) whether the issuance of any additional shares, or of any shares
of any other series, shall be subject to restrictions as to issuance, or as to
the powers, preferences or rights of any such other series; and (ix) any other
preferences, privileges and powers and relative, participating, optional or
other special rights and qualifications, limitations or restrictions.

                                        1

<PAGE>   3


COMMON STOCK

         Dividend Rights

         Subject to any prior rights of any holders of Preferred Stock then
outstanding, the holders of the Common Stock will be entitled to dividends when,
as and if declared by the Company's Board of Directors out of funds legally
available therefor. Under Michigan law, dividends may be legally declared or
paid only if after the distribution the Company can pay its debts as they come
due in the usual course of business and the Company's total assets equal or
exceed the sum of its liabilities plus the amount that would be needed to
satisfy the preferential rights upon dissolution of any holders of preferred
stock then outstanding whose preferential rights are superior to those receiving
the distribution.

         Funds for the payment of dividends by the Company are expected to be
obtained primarily from dividends of Mercantile Bank of West Michigan (the
"Bank"), the Company's subsidiary. There can be no assurance that the Company
will have funds available for dividends, or that if funds are available, that
dividends will be declared by the Company's Board of Directors.

         Voting Rights

         Subject to the rights, if any, of holders of shares of Preferred Stock
then outstanding, all voting rights are vested in the holders of shares of
Common Stock. Each share of Common Stock entitles the holder thereof to one vote
on all matters, including the election of directors. Shareholders of the Company
do not have cumulative voting rights.

         Preemptive Rights

         Holders of Common Stock do not have preemptive rights.

         Liquidation Rights

         Subject to any rights of any Preferred Stock then outstanding, holders
of Common Stock are entitled to share on a pro rata basis in the net assets of
the Company which remain after satisfaction of all liabilities.

         Transfer Agent

         State Street Bank & Trust Company of Boston, Massachusetts, serves as
the transfer agent of the Company's Common Stock.

CERTAIN CHARTER PROVISIONS

         The following provisions of the Company's Articles of Incorporation may
delay, defer, prevent, or make it more difficult for a person to acquire the
Company or to change control of the Company's Board of Directors, thereby
reducing the Company's vulnerability to an unsolicited takeover attempt.

         Classification of the Board of Directors

         The Company's Articles of Incorporation provide for the Board of
Directors to be divided into three classes with staggered terms; each class to
be as nearly equal in number as possible. Each director is elected for a three
year term. Approximately one-third of the Board positions are filled by a
shareholder vote each year. Any vacancies in the Board, or newly created
director positions, may be filled by vote of the directors then in office. The
Company's Articles of Incorporation provide that the number of directors shall
be fixed by majority of the Board at no fewer than six nor more than fifteen.

                                       2

<PAGE>   4


         Removal of Directors

         The Michigan Business Corporation Act ("MBCA") provides that, unless
the articles of incorporation otherwise provide, shareholders may remove a
director or the entire Board of Directors with or without cause. The Company's
Articles of Incorporation provide that a director may be removed only for cause
and only by the affirmative vote of the holders of a majority of the voting
power of all the shares of the Company entitled to vote generally in the
election of directors.

         Filling Vacancies on the Board of Directors

         The Company's Articles of Incorporation provide that a new director
chosen to fill a vacancy on the Board of Directors will serve for the remainder
of the full term of the class in which the vacancy occurred.

         Nominations of Director Candidates

         The Company's Articles of Incorporation include a provision governing
nominations of director candidates. Nominations for the election of directors
may be made by the Board of Directors, a nominating committee appointed by the
Board of Directors, or any shareholder entitled to vote for directors. In the
case of a shareholder nomination, the Articles of Incorporation provide certain
procedures that must be followed. A shareholder intending to nominate candidates
for election must deliver written notice containing certain specified
information to the Secretary of the Company at least sixty (60) days but not
more than ninety (90) days prior to the anniversary date of the immediately
preceding annual meeting of shareholders.

         Certain Shareholder Action

         The Company's Articles of Incorporation require that any shareholder
action must be taken at an annual or special meeting of shareholders, that any
meeting of shareholders must be called by the Board of Directors or the Chairman
of the Board, and, unless otherwise provided by law, prohibit shareholder action
by written consent. Shareholders of the Company are not permitted to call a
special meeting of shareholders or require that the Board call such a special
meeting. The MBCA permits shareholders holding 10% or more of all of the shares
entitled to vote at a meeting to request the Circuit Court of the County in
which the Company's principal place of business or registered office is located
to order a special meeting of shareholders for good cause shown.

         Increased Shareholders Vote for Alteration, Amendment or Repeal of
Article Provisions

         The Company's Articles of Incorporation require the affirmative vote of
the holders of at least 66 2/3 percent of the voting stock of the Company
entitled to vote generally in the election of directors for the alteration,
amendment or repeal of, or the adoption of any provision inconsistent with the
foregoing provisions of the Company's Articles of Incorporation.

                                       3

<PAGE>   5


CERTAIN ANTI-TAKEOVER PROVISIONS

         Michigan Fair Price Act

         Certain provisions of the MBCA establish a statutory scheme similar to
the supermajority and fair price provisions found in many corporate charters
(the "Fair Price Act"). The Fair Price Act provides that a supermajority vote of
90 percent of the shareholders and no less than two-thirds of the votes of
noninterested shareholders must approve a "business combination." The Fair Price
Act defines a "business combination" to encompass any merger, consolidation,
share exchange, sale of assets, stock issue, liquidation, or reclassification of
securities involving an "interested shareholder" or certain "affiliates." An
"interested shareholder" is generally any person who owns 10 percent or more of
the outstanding voting shares of the Company. An "affiliate" is a person who
directly or indirectly controls, is controlled by, or is under common control
with, a specified person.

         The supermajority vote required by the Fair Price Act does not apply to
business combinations that satisfy certain conditions. These conditions include,
among others: (i) the purchase price to be paid for the shares of the Company in
the business combination must be at least equal to the highest of either (a) the
market value of the shares or (b) the highest per share price paid by the
interested shareholder within the preceding two-year period or in the
transaction in which the shareholder became an interested shareholder, whichever
is higher; (ii) once becoming an interested shareholder, the person may not
become the beneficial owner of any additional shares of the Company except as
part of the transaction which resulted in the interested shareholder becoming an
interested shareholder or by virtue of proportionate stock splits or stock
dividends; and (iii) five years must have elapsed since the person involved
became an interested shareholder.

         The requirements of the Fair Price Act do not apply to business
combinations with an interested shareholder that the Board of Directors has
approved or exempted from the requirements of the Fair Price Act by resolution
prior to the time that the interested shareholder first became an interested
shareholder.

         Control Share Act.

         The MBCA regulates the acquisition of "control shares" of large public
Michigan corporations (the "Control Share Act"). The Control Share Act
establishes procedures governing "control share acquisitions." A control share
acquisition is defined as an acquisition of shares by an acquiror which, when
combined with other shares held by that person or entity, would give the
acquiror voting power, alone or as part of a group, at or above any of the
following thresholds: 20 percent, 33-1/3 percent or 50 percent. Under the
Control Share Act, an acquiror may not vote "control shares" unless the
Company's disinterested shareholders (defined to exclude the acquiring person,
officers of the target Company, and directors of the target Company who are also
employees of the Company) vote to confer voting rights on the control shares.
The Control Share Act does not affect the voting rights of shares owned by an
acquiring person prior to the control share acquisition.

         The Control Share Act entitles corporations to redeem control shares
from the acquiring person under certain circumstances. In other cases, the
Control Share Act confers dissenters' right upon all of the corporation's
shareholders except the acquiring person.

ITEM 5.  INTEREST OF NAMED EXPERTS AND COUNSEL

Not Applicable.

                                        4

<PAGE>   6


ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS

         Indemnification

         The Company's Articles of Incorporation provide that the Company shall
indemnify its present and past directors, officers, and such other persons as
the Board of Directors may authorize to the full extent permitted by law.

         The Company's Bylaws contain indemnification provisions concerning
third party actions as well as actions in the right of the Company. The Bylaws
provide that the Company shall indemnify any person who was or is a party or is
threatened to be made a party to any threatened, pending or completed action,
suit or proceeding, whether civil, criminal, administrative or investigative
(other than an action by or in the right of the Company) by reason of the fact
that he or she is or was a director or officer of the Company or while serving
as such a director or officer, is or was serving at the request of the Company
as a director, officer, partner, trustee, employee or agent of another foreign
or domestic corporation, partnership, joint venture, trust or other enterprise,
whether for profit or not, against expenses (including attorney's fees),
judgments. penalties, fees and amounts paid in settlement actually and
reasonably incurred by him or her in connection with such action, suit or
proceeding if he or she acted in good faith and in a manner he or she reasonably
believed to be in or not opposed to the best interests of the Company or its
shareholders and, with respect to any criminal action or proceeding, had no
reasonable cause to believe his or her conduct was unlawful.

         FDIC regulations impose limitations on indemnification payments which
could restrict, in certain circumstances, payments by the Company or the Bank to
their respective directors or officers otherwise permitted under the MBCA or the
Michigan Banking Code, respectively.

         With respect to derivative actions, the Bylaws provide that the Company
shall indemnify any person who was or is a party to or is threatened to be made
a party to any threatened, pending or completed action or suit by or in the
right of the Company to procure a judgment in its favor by reason of the fact
that he or she is or was a director or officer of the Company, or while serving
as such a director or officer, is or was serving at the request of the Company
as a director, officer, partner, trustee, employee or agent of another foreign
or domestic corporation. partnership, joint venture, trust or other enterprise,
whether for profit or not, against expenses (including attorney's fees) and
amounts paid in settlement actually and reasonably incurred by him or her in
connection with the action or suit if he or she acted in good faith and in a
manner he or she reasonably believed to be in or not opposed to the best
interests of the Company or its shareholders. No indemnification is provided in
the Bylaws in respect of any claim, issue or matter in which such person has
been found liable to the Company except to the extent that a court of competent
jurisdiction determines upon application that, despite the adjudication of
liability but in view of all circumstances of the case, such person is fairly
and reasonably entitled to indemnity for such expenses which such court shall
deem proper.

         Insofar as indemnification for liabilities arising under the Securities
Act of 1933 may be permitted to directors, officers and controlling persons of
the Company pursuant to the provisions discussed above or otherwise, the Company
has been advised that in the opinion of the Securities and Exchange Commission
such indemnification is against public policy as expressed in the Securities Act
of 1933 and is, therefore, unenforceable.

         The Company has purchased directors' and officers' liability insurance
for directors and officers of the Company.

                                       5

<PAGE>   7


         Limitation of Director Liability

         The MBCA permits corporations to limit the personal liability of their
directors in certain circumstances. The Company's Articles of Incorporation
provide that the director of the Company shall not be personally liable to the
Company or its shareholders for monetary damages for breach of the director's
fiduciary duty. However, they do not eliminate or limit the liability of a
director for any breach of a duty, act or omission for which the elimination or
limitation of liability is not permitted by the MBCA, currently including,
without limitation, the following: (1) breach of the director's duty of loyalty
to the Company or its shareholders; (2) acts or omissions not in good faith or
that involve intentional misconduct or a knowing violation of the law; (3)
illegal loans, distributions of dividends or assets, or stock purchases as
described in Section 551(1) of the MBCA; and (4) transactions from which the
director derived an improper personal benefit.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED

Not Applicable

ITEM 8.  EXHIBITS

The following exhibits are filed herewith:

               Exhibit
               Number                                Exhibit

                  4                         Article  III  of the  Articles  of  
                                            Incorporation of the Company is
                                            incorporated by reference to Exhibit
                                            3.1 of the Company's Registration
                                            Statement on Form SB-2 (Commission
                                            File No. 333-33081) that became
                                            effective on October 23, 1997

                  5                         Copy of the Internal Revenue Service
                                            determination letter that the Plan
                                            is qualified under section 401 of
                                            the Internal Revenue Code

                 23                         Consent of Crowe, Chizek and Company
                                            LLP

ITEM 9.  UNDERTAKINGS

         The undersigned registrant hereby undertakes:

         (1) To file, during any period in which offers or sales are being made,
a post-effective amendment to this Registration Statement: (i) to include any
Prospectus required by Section 10(a)(3) of the Securities Act of 1933; (ii) to
reflect in the Prospectus any facts or events arising after the effective date
of the Registration Statement (or the most recent post-effective amendment
thereof) which, individually or in the aggregate, represent a fundamental change
in the information set forth in the Registration Statement, provided that any
increase or decrease in volume of securities offered (if the total dollar value
of securities offered would not exceed that which was registered) and any
deviation from the low or high end of the estimated maximum offering range may
be reflected in the form of prospectus filed with the Commission pursuant to
Rule 424(b), if in the aggregate, the changes in volume and price represent no
more than a 20% change in the maximum aggregate offering price set forth in the
"Calculation of Registration Fee" table in the effective registration statement;
(iii) to include any material information with respect to the plan of
distribution not previously disclosed in the Registration Statement or any
material change to such information in the Registration Statement; provided,
however, that paragraphs (1)(i) and (1)(ii) do not apply if the information
required to be included in a post-effective amendment by those paragraphs is
contained in periodic reports filed with or furnished to the Commission by the

                                       6
<PAGE>   8


Registrant pursuant to Section 13 or Section 15(d) of the Securities Exchange
Act of 1934 that are incorporated by reference in the Registration Statement.

         (2) That, for purposes of determining any liability under the
Securities Act of 1933, each such post-effective amendment shall be deemed to be
a new Registration Statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

         (3) To remove from registration by means of a post-effective amendment
any of the securities being registered which remain unsold at the termination of
the offering.

         The undersigned Registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act of 1933, each filing of the
Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Securities Exchange Act of 1934 (and, where applicable, each filing of an
employee benefit plan's annual report pursuant to Section 15(d) of the
Securities Exchange Act of 1934) that is incorporated by reference in the
Registration Statement shall be deemed to be a new Registration Statement
relating to the securities offered therein, and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof.

         Insofar as indemnification for liabilities arising under the Securities
Act of 1933 may be permitted to directors, officers and controlling persons of
the Registrant pursuant to the foregoing provisions, or otherwise, the
Registrant has been advised that in the opinion of the Securities and Exchange
Commission such indemnification is against public policy as expressed in the Act
and is, therefore, unenforceable. In the event that a claim for indemnification
against such liabilities (other than the payment by the Registrant of expenses
incurred or paid by a director, officer or controlling person of the Registrant,
in the successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the Registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question of whether or not such indemnification by it is
against public policy as expressed in the Act and will be governed by the final
adjudication of such issue.


                                       7

<PAGE>   9





                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, the
Registrant certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City Grand Rapids and State of Michigan on March 31, 1999.

                               MERCANTILE BANK CORPORATION

                               By  /S/ GERALD R. JOHNSON
                                   ---------------------
                                   Gerald R. Johnson, Jr., Chairman of the Board
                                   and Chief Executive Officer

Pursuant to the requirements of the Securities Act of 1933, this Registration
Statement has been signed by the following persons in the capacities indicated
on March 31, 1999.

<TABLE>
<S><C>


/S/ BETTY S. BURTON                                          
-------------------                                          ------------------------------
Betty S. Burton, Director                                    Lawrence W. Larsen, Director

/S/EDWARD J. CLARK                                           /S/CALVIN D. MURDOCK
------------------                                           --------------------
Edward J. Clark, Director                                    Calvin D. Murdock, Director

/S/ PETER A. CORDES                                          /S/MICHAEL H. PRICE
-------------------                                          -------------------
Peter A. Cordes, Director                                    Michael H. Price, President and Chief Operating Officer

/S/C. JOHN GILL                                              
---------------                                              ------------------------------
C. John Gill, Director                                       Dale J. Visser, Director


/s/ David M. Hecht                                           /S/DONALD WILLIAMS, SR.
--------------------------------                             -----------------------
David M. Hecht, Director                                     Donald Williams, Sr., Director

/S/GERALD R. JOHNSON, JR.                                    
-------------------------                                    ------------------------------
Gerald R. Johnson, Jr., Chairman of the                      Robert M. Wynalda, Director
Board and Chief Executive Officer
(principal executive officer)

/S/SUSAN K. JONES                                            /S/CHARLES E. CHRISTMAS
-----------------                                            -----------------------
Susan K. Jones, Director                                     Charles E. Christmas, Chief Financial Officer,
                                                             Treasurer and Compliance Officer (principal financial
                                                             and accounting officer)
</TABLE>


                                       8

<PAGE>   10


                                    SIGNATURE



         Pursuant to the requirements of the Securities Act of 1933, the trustee
(or other persons who administer the employee benefit plan) have duly caused
this registration statement to be signed on its behalf by the undersigned,
thereunto duly authorized, in the City of Grand Rapids, State of Michigan on
this 31st day of March 1999.

                                 MERCANTILE BANK OF WEST MICHIGAN 401(k) PLAN

                                 By  /S/ GERALD R. JOHNSON, JR.
                                     -------------------------------
                                     Gerald R. Johnson, Jr., Trustee


                                       9
<PAGE>   11


                                  EXHIBIT INDEX



Exhibit

Number                                      Exhibit

   4                                        Article  III  of the  Articles  of  
                                            Incorporation of the Company is
                                            incorporated by reference to Exhibit
                                            3.1 of the Company's Registration
                                            Statement on Form SB-2 (Commission
                                            File No. 333-33081) that became
                                            effective on October 23, 1997

   5                                        Copy of the Internal Revenue Service
                                            determination letter that the Plan
                                            is qualified under Section 401 of
                                            the Internal Revenue Code

   23                                       Consent of Crowe, Chizek and Company
                                            LLP
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 31611}]
{"company-data": {"conformed-name": "MERCANTILE BANK CORP", "cik": "0001042729", "assigned-sic": "6022", "irs-number": "383360865", "state-of-incorporation": "MI", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-75521", "film-number": "99586329"}, "business-address": {"street1": "42 DEER RUN DRIVE", "city": "ADA", "state": "MI", "zip": "49301", "phone": "6166760201"}, "mail-address": {"street1": "42 DEER RUN DRIVE", "city": "ADA", "state": "MI", "zip": "49301"}}
1
                                                          Registration No. 333--

                     U.S. SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      Under
                           The Securities Act of 1933

                             -----------------------

                           MERCANTILE BANK CORPORATION
              (Exact number of issuer as specified in its charter)

        Michigan                                      38-3360865
(State or other jurisdiction of             (I.R.S. Employer Identification No.)
of incorporation or organization)

             216 North Division Avenue, Grand Rapids, Michigan 49503
               (Address of Principal Executive Offices) (Zip Code)

                  MERCANTILE BANK OF WEST MICHIGAN 401(K) PLAN
                            (Full title of the plan)

                        GERALD R. JOHNSON, JR., CHAIRMAN
                           Mercantile Bank Corporation
                            216 North Division Avenue
                          Grand Rapids, Michigan 49503
                     (Name and Address of Agent for service)
          Telephone number, including area code, of agent for service:
                                 (616) 242-9000

                          COPIES OF COMMUNICATIONS TO:
                               JEROME M. SCHWARTZ
                              Dickinson Wright PLLC
                         500 Woodward Avenue, Suite 4000
                             Detroit, Michigan 48226

                  Approximate date of proposed public offering:
 As soon as practicable after the effective date of this Registration Statement

                         CALCULATION OF REGISTRATION FEE
-------------------------------- ---------------------- ------------------------- ------------------------ -----------------
                                                            Proposed Maximum             Proposed
      Title of Securities            Amount to be           Offering Price Per       Maximum Aggregate        Amount of
       to be Registered*              Registered                Share**              Offering Price**      Registration Fee
-------------------------------- ---------------------- ------------------------- ------------------------ -----------------
Common Stock                50,000 Shares               $14.00                  $700,000                $195
-------------------------------- ---------------------- ------------------------- ------------------------ -----------------
*In addition, pursuant to Rule 416(c) under the Securities Act of 1933, this
registration statement also covers an indeterminate amount of interests to be
offered or sold pursuant to the employee benefit plan described herein.
**Based upon the average of the bid and ask prices on March 30, 1999
2

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

         Mercantile Bank Corporation (the "Company") and the Mercantile Bank of
West Michigan 401(k) Plan (the "Plan") hereby incorporate by reference in this
Registration Statement the following document previously filed with the
Securities and Exchange Commission (the "Commission") under the Securities
Exchange Act of 1934, as amended (the "Exchange Act"):

         1. The Company's Annual Report on Form 10-KSB for the year ended
December 31, 1998.

         All documents subsequently filed with the Commission by the Company or
the Plan pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act
prior to the filing of a post-effective amendment which indicates that all
securities offered hereby have been sold or which deregisters all securities
then remaining unsold shall be deemed to be incorporated herein by reference and
to be a part hereof from the dates of filing of such documents.

ITEM 4.  DESCRIPTION OF SECURITIES

         The Company's authorized capital stock consists of 9,000,000 shares of
Common Stock and 1,000,000 shares of Preferred Stock. As of the date of this
Registration Statement, there are 2,472,500 shares of Common Stock issued and
outstanding. No shares of Preferred Stock have been issued by the Company.

         Michigan law allows the Company's Board of Directors to issue
additional shares of stock up to the total amount of Common Stock and Preferred
Stock authorized without obtaining the prior approval of the shareholders.

PREFERRED STOCK

         The Board of Directors of the Company is authorized to issue Preferred
Stock, in one or more series, from time to time, with such voting powers, full
or limited but not to exceed one vote per share, or without voting powers, and
with such designations, preferences and relative, participating, optional or
other special rights, and qualifications, limitation or restrictions thereof, as
may be provided in the resolution or resolutions adopted by the Board of
Directors. The authority of the Board of Directors includes, but is not limited
to, the determination or fixing of the following with respect to shares of such
class or any series thereof: (i) the number of shares and designation of such
series; (ii) the dividend rate and whether dividends are to be cumulative; (iii)
whether shares are to be redeemable, and, if so, whether redeemable for cash,
property or rights; (iv) the rights to which the holders of shares shall be
entitled, and the preferences, if any, over any other series; (v) whether the
shares shall be subject to the operation of a purchase, retirement or sinking
fund, and, if so, upon what conditions; (vi) whether the shares shall be
convertible into or exchangeable for shares of any other class or of any other
series of any class of capital stock and the terms and conditions of such
conversion or exchange; (vii) the voting powers, full or limited, if any, of the
shares; (viii) whether the issuance of any additional shares, or of any shares
of any other series, shall be subject to restrictions as to issuance, or as to
the powers, preferences or rights of any such other series; and (ix) any other
preferences, privileges and powers and relative, participating, optional or
other special rights and qualifications, limitations or restrictions.

                                        1
3

COMMON STOCK

         Dividend Rights

         Subject to any prior rights of any holders of Preferred Stock then
outstanding, the holders of the Common Stock will be entitled to dividends when,
as and if declared by the Company's Board of Directors out of funds legally
available therefor. Under Michigan law, dividends may be legally declared or
paid only if after the distribution the Company can pay its debts as they come
due in the usual course of business and the Company's total assets equal or
exceed the sum of its liabilities plus the amount that would be needed to
satisfy the preferential rights upon dissolution of any holders of preferred
stock then outstanding whose preferential rights are superior to those receiving
the distribution.

         Funds for the payment of dividends by the Company are expected to be
obtained primarily from dividends of Mercantile Bank of West Michigan (the
"Bank"), the Company's subsidiary. There can be no assurance that the Company
will have funds available for dividends, or that if funds are available, that
dividends will be declared by the Company's Board of Directors.

         Voting Rights

         Subject to the rights, if any, of holders of shares of Preferred Stock
then outstanding, all voting rights are vested in the holders of shares of
Common Stock. Each share of Common Stock entitles the holder thereof to one vote
on all matters, including the election of directors. Shareholders of the Company
do not have cumulative voting rights.

         Preemptive Rights

         Holders of Common Stock do not have preemptive rights.

         Liquidation Rights

         Subject to any rights of any Preferred Stock then outstanding, holders
of Common Stock are entitled to share on a pro rata basis in the net assets of
the Company which remain after satisfaction of all liabilities.

         Transfer Agent

         State Street Bank & Trust Company of Boston, Massachusetts, serves as
the transfer agent of the Company's Common Stock.

CERTAIN CHARTER PROVISIONS

         The following provisions of the Company's Articles of Incorporation may
delay, defer, prevent, or make it more difficult for a person to acquire the
Company or to change control of the Company's Board of Directors, thereby
reducing the Company's vulnerability to an unsolicited takeover attempt.

         Classification of the Board of Directors

         The Company's Articles of Incorporation provide for the Board of
Directors to be divided into three classes with staggered terms; each class to
be as nearly equal in number as possible. Each director is elected for a three
year term. Approximately one-third of the Board positions are filled by a
shareholder vote each year. Any vacancies in the Board, or newly created
director positions, may be filled by vote of the directors then in office. The
Company's Articles of Incorporation provide that the number of directors shall
be fixed by majority of the Board at no fewer than six nor more than fifteen.

                                       2
4

         Removal of Directors

         The Michigan Business Corporation Act ("MBCA") provides that, unless
the articles of incorporation otherwise provide, shareholders may remove a
director or the entire Board of Directors with or without cause. The Company's
Articles of Incorporation provide that a director may be removed only for cause
and only by the affirmative vote of the holders of a majority of the voting
power of all the shares of the Company entitled to vote generally in the
election of directors.

         Filling Vacancies on the Board of Directors

         The Company's Articles of Incorporation provide that a new director
chosen to fill a vacancy on the Board of Directors will serve for the remainder
of the full term of the class in which the vacancy occurred.

         Nominations of Director Candidates

         The Company's Articles of Incorporation include a provision governing
nominations of director candidates. Nominations for the election of directors
may be made by the Board of Directors, a nominating committee appointed by the
Board of Directors, or any shareholder entitled to vote for directors. In the
case of a shareholder nomination, the Articles of Incorporation provide certain
procedures that must be followed. A shareholder intending to nominate candidates
for election must deliver written notice containing certain specified
information to the Secretary of the Company at least sixty (60) days but not
more than ninety (90) days prior to the anniversary date of the immediately
preceding annual meeting of shareholders.

         Certain Shareholder Action

         The Company's Articles of Incorporation require that any shareholder
action must be taken at an annual or special meeting of shareholders, that any
meeting of shareholders must be called by the Board of Directors or the Chairman
of the Board, and, unless otherwise provided by law, prohibit shareholder action
by written consent. Shareholders of the Company are not permitted to call a
special meeting of shareholders or require that the Board call such a special
meeting. The MBCA permits shareholders holding 10% or more of all of the shares
entitled to vote at a meeting to request the Circuit Court of the County in
which the Company's principal place of business or registered office is located
to order a special meeting of shareholders for good cause shown.

         Increased Shareholders Vote for Alteration, Amendment or Repeal of
Article Provisions

         The Company's Articles of Incorporation require the affirmative vote of
the holders of at least 66 2/3 percent of the voting stock of the Company
entitled to vote generally in the election of directors for the alteration,
amendment or repeal of, or the adoption of any provision inconsistent with the
foregoing provisions of the Company's Articles of Incorporation.

                                       3
5

CERTAIN ANTI-TAKEOVER PROVISIONS

         Michigan Fair Price Act

         Certain provisions of the MBCA establish a statutory scheme similar to
the supermajority and fair price provisions found in many corporate charters
(the "Fair Price Act"). The Fair Price Act provides that a supermajority vote of
90 percent of the shareholders and no less than two-thirds of the votes of
noninterested shareholders must approve a "business combination." The Fair Price
Act defines a "business combination" to encompass any merger, consolidation,
share exchange, sale of assets, stock issue, liquidation, or reclassification of
securities involving an "interested shareholder" or certain "affiliates." An
"interested shareholder" is generally any person who owns 10 percent or more of
the outstanding voting shares of the Company. An "affiliate" is a person who
directly or indirectly controls, is controlled by, or is under common control
with, a specified person.

         The supermajority vote required by the Fair Price Act does not apply to
business combinations that satisfy certain conditions. These conditions include,
among others: (i) the purchase price to be paid for the shares of the Company in
the business combination must be at least equal to the highest of either (a) the
market value of the shares or (b) the highest per share price paid by the
interested shareholder within the preceding two-year period or in the
transaction in which the shareholder became an interested shareholder, whichever
is higher; (ii) once becoming an interested shareholder, the person may not
become the beneficial owner of any additional shares of the Company except as
part of the transaction which resulted in the interested shareholder becoming an
interested shareholder or by virtue of proportionate stock splits or stock
dividends; and (iii) five years must have elapsed since the person involved
became an interested shareholder.

         The requirements of the Fair Price Act do not apply to business
combinations with an interested shareholder that the Board of Directors has
approved or exempted from the requirements of the Fair Price Act by resolution
prior to the time that the interested shareholder first became an interested
shareholder.

         Control Share Act.

         The MBCA regulates the acquisition of "control shares" of large public
Michigan corporations (the "Control Share Act"). The Control Share Act
establishes procedures governing "control share acquisitions." A control share
acquisition is defined as an acquisition of shares by an acquiror which, when
combined with other shares held by that person or entity, would give the
acquiror voting power, alone or as part of a group, at or above any of the
following thresholds: 20 percent, 33-1/3 percent or 50 percent. Under the
Control Share Act, an acquiror may not vote "control shares" unless the
Company's disinterested shareholders (defined to exclude the acquiring person,
officers of the target Company, and directors of the target Company who are also
employees of the Company) vote to confer voting rights on the control shares.
The Control Share Act does not affect the voting rights of shares owned by an
acquiring person prior to the control share acquisition.

         The Control Share Act entitles corporations to redeem control shares
from the acquiring person under certain circumstances. In other cases, the
Control Share Act confers dissenters' right upon all of the corporation's
shareholders except the acquiring person.

ITEM 5.  INTEREST OF NAMED EXPERTS AND COUNSEL

Not Applicable.

                                        4
6

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS

         Indemnification

         The Company's Articles of Incorporation provide that the Company shall
indemnify its present and past directors, officers, and such other persons as
the Board of Directors may authorize to the full extent permitted by law.

         The Company's Bylaws contain indemnification provisions concerning
third party actions as well as actions in the right of the Company. The Bylaws
provide that the Company shall indemnify any person who was or is a party or is
threatened to be made a party to any threatened, pending or completed action,
suit or proceeding, whether civil, criminal, administrative or investigative
(other than an action by or in the right of the Company) by reason of the fact
that he or she is or was a director or officer of the Company or while serving
as such a director or officer, is or was serving at the request of the Company
as a director, officer, partner, trustee, employee or agent of another foreign
or domestic corporation, partnership, joint venture, trust or other enterprise,
whether for profit or not, against expenses (including attorney's fees),
judgments. penalties, fees and amounts paid in settlement actually and
reasonably incurred by him or her in connection with such action, suit or
proceeding if he or she acted in good faith and in a manner he or she reasonably
believed to be in or not opposed to the best interests of the Company or its
shareholders and, with respect to any criminal action or proceeding, had no
reasonable cause to believe his or her conduct was unlawful.

         FDIC regulations impose limitations on indemnification payments which
could restrict, in certain circumstances, payments by the Company or the Bank to
their respective directors or officers otherwise permitted under the MBCA or the
Michigan Banking Code, respectively.

         With respect to derivative actions, the Bylaws provide that the Company
shall indemnify any person who was or is a party to or is threatened to be made
a party to any threatened, pending or completed action or suit by or in the
right of the Company to procure a judgment in its favor by reason of the fact
that he or she is or was a director or officer of the Company, or while serving
as such a director or officer, is or was serving at the request of the Company
as a director, officer, partner, trustee, employee or agent of another foreign
or domestic corporation. partnership, joint venture, trust or other enterprise,
whether for profit or not, against expenses (including attorney's fees) and
amounts paid in settlement actually and reasonably incurred by him or her in
connection with the action or suit if he or she acted in good faith and in a
manner he or she reasonably believed to be in or not opposed to the best
interests of the Company or its shareholders. No indemnification is provided in
the Bylaws in respect of any claim, issue or matter in which such person has
been found liable to the Company except to the extent that a court of competent
jurisdiction determines upon application that, despite the adjudication of
liability but in view of all circumstances of the case, such person is fairly
and reasonably entitled to indemnity for such expenses which such court shall
deem proper.

         Insofar as indemnification for liabilities arising under the Securities
Act of 1933 may be permitted to directors, officers and controlling persons of
the Company pursuant to the provisions discussed above or otherwise, the Company
has been advised that in the opinion of the Securities and Exchange Commission
such indemnification is against public policy as expressed in the Securities Act
of 1933 and is, therefore, unenforceable.

         The Company has purchased directors' and officers' liability insurance
for directors and officers of the Company.

                                       5
7

         Limitation of Director Liability

         The MBCA permits corporations to limit the personal liability of their
directors in certain circumstances. The Company's Articles of Incorporation
provide that the director of the Company shall not be personally liable to the
Company or its shareholders for monetary damages for breach of the director's
fiduciary duty. However, they do not eliminate or limit the liability of a
director for any breach of a duty, act or omission for which the elimination or
limitation of liability is not permitted by the MBCA, currently including,
without limitation, the following: (1) breach of the director's duty of loyalty
to the Company or its shareholders; (2) acts or omissions not in good faith or
that involve intentional misconduct or a knowing violation of the law; (3)
illegal loans, distributions of dividends or assets, or stock purchases as
described in Section 551(1) of the MBCA; and (4) transactions from which the
director derived an improper personal benefit.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED

Not Applicable

ITEM 8.  EXHIBITS

The following exhibits are filed herewith:

               Exhibit
               Number                                Exhibit

                  4                         Article  III  of the  Articles  of  
                                            Incorporation of the Company is
                                            incorporated by reference to Exhibit
                                            3.1 of the Company's Registration
                                            Statement on Form SB-2 (Commission
                                            File No. 333-33081) that became
                                            effective on October 23, 1997

                  5                         Copy of the Internal Revenue Service
                                            determination letter that the Plan
                                            is qualified under section 401 of
                                            the Internal Revenue Code

                 23                         Consent of Crowe, Chizek and Company
                                            LLP

ITEM 9.  UNDERTAKINGS

         The undersigned registrant hereby undertakes:

         (1) To file, during any period in which offers or sales are being made,
a post-effective amendment to this Registration Statement: (i) to include any
Prospectus required by Section 10(a)(3) of the Securities Act of 1933; (ii) to
reflect in the Prospectus any facts or events arising after the effective date
of the Registration Statement (or the most recent post-effective amendment
thereof) which, individually or in the aggregate, represent a fundamental change
in the information set forth in the Registration Statement, provided that any
increase or decrease in volume of securities offered (if the total dollar value
of securities offered would not exceed that which was registered) and any
deviation from the low or high end of the estimated maximum offering range may
be reflected in the form of prospectus filed with the Commission pursuant to
Rule 424(b), if in the aggregate, the changes in volume and price represent no
more than a 20% change in the maximum aggregate offering price set forth in the
"Calculation of Registration Fee" table in the effective registration statement;
(iii) to include any material information with respect to the plan of
distribution not previously disclosed in the Registration Statement or any
material change to such information in the Registration Statement; provided,
however, that paragraphs (1)(i) and (1)(ii) do not apply if the information
required to be included in a post-effective amendment by those paragraphs is
contained in periodic reports filed with or furnished to the Commission by the

                                       6
8

Registrant pursuant to Section 13 or Section 15(d) of the Securities Exchange
Act of 1934 that are incorporated by reference in the Registration Statement.

         (2) That, for purposes of determining any liability under the
Securities Act of 1933, each such post-effective amendment shall be deemed to be
a new Registration Statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

         (3) To remove from registration by means of a post-effective amendment
any of the securities being registered which remain unsold at the termination of
the offering.

         The undersigned Registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act of 1933, each filing of the
Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Securities Exchange Act of 1934 (and, where applicable, each filing of an
employee benefit plan's annual report pursuant to Section 15(d) of the
Securities Exchange Act of 1934) that is incorporated by reference in the
Registration Statement shall be deemed to be a new Registration Statement
relating to the securities offered therein, and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof.

         Insofar as indemnification for liabilities arising under the Securities
Act of 1933 may be permitted to directors, officers and controlling persons of
the Registrant pursuant to the foregoing provisions, or otherwise, the
Registrant has been advised that in the opinion of the Securities and Exchange
Commission such indemnification is against public policy as expressed in the Act
and is, therefore, unenforceable. In the event that a claim for indemnification
against such liabilities (other than the payment by the Registrant of expenses
incurred or paid by a director, officer or controlling person of the Registrant,
in the successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the Registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question of whether or not such indemnification by it is
against public policy as expressed in the Act and will be governed by the final
adjudication of such issue.

                                       7
9

                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, the
Registrant certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City Grand Rapids and State of Michigan on March 31, 1999.

                               MERCANTILE BANK CORPORATION

                               By  /S/ GERALD R. JOHNSON
                                   ---------------------
                                   Gerald R. Johnson, Jr., Chairman of the Board
                                   and Chief Executive Officer

Pursuant to the requirements of the Securities Act of 1933, this Registration
Statement has been signed by the following persons in the capacities indicated
on March 31, 1999.
/S/ BETTY S. BURTON                                          
-------------------                                          ------------------------------
Betty S. Burton, Director                                    Lawrence W. Larsen, Director

/S/EDWARD J. CLARK                                           /S/CALVIN D. MURDOCK
------------------                                           --------------------
Edward J. Clark, Director                                    Calvin D. Murdock, Director

/S/ PETER A. CORDES                                          /S/MICHAEL H. PRICE
-------------------                                          -------------------
Peter A. Cordes, Director                                    Michael H. Price, President and Chief Operating Officer

/S/C. JOHN GILL                                              
---------------                                              ------------------------------
C. John Gill, Director                                       Dale J. Visser, Director

/s/ David M. Hecht                                           /S/DONALD WILLIAMS, SR.
--------------------------------                             -----------------------
David M. Hecht, Director                                     Donald Williams, Sr., Director

/S/GERALD R. JOHNSON, JR.                                    
-------------------------                                    ------------------------------
Gerald R. Johnson, Jr., Chairman of the                      Robert M. Wynalda, Director
Board and Chief Executive Officer
(principal executive officer)

/S/SUSAN K. JONES                                            /S/CHARLES E. CHRISTMAS
-----------------                                            -----------------------
Susan K. Jones, Director                                     Charles E. Christmas, Chief Financial Officer,
                                                             Treasurer and Compliance Officer (principal financial
                                                             and accounting officer)
8
10

                                    SIGNATURE

         Pursuant to the requirements of the Securities Act of 1933, the trustee
(or other persons who administer the employee benefit plan) have duly caused
this registration statement to be signed on its behalf by the undersigned,
thereunto duly authorized, in the City of Grand Rapids, State of Michigan on
this 31st day of March 1999.

                                 MERCANTILE BANK OF WEST MICHIGAN 401(k) PLAN

                                 By  /S/ GERALD R. JOHNSON, JR.
                                     -------------------------------
                                     Gerald R. Johnson, Jr., Trustee

                                       9
11

                                  EXHIBIT INDEX

Exhibit

Number                                      Exhibit

   4                                        Article  III  of the  Articles  of  
                                            Incorporation of the Company is
                                            incorporated by reference to Exhibit
                                            3.1 of the Company's Registration
                                            Statement on Form SB-2 (Commission
                                            File No. 333-33081) that became
                                            effective on October 23, 1997

   5                                        Copy of the Internal Revenue Service
                                            determination letter that the Plan
                                            is qualified under Section 401 of
                                            the Internal Revenue Code

   23                                       Consent of Crowe, Chizek and Company
                                            LLP