<PAGE>   1

===============================================================================



                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549


                                  FORM 10-QSB


                QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d)
                     OF THE SECURITIES EXCHANGE ACT OF 1934


For Quarterly Period Ended                    Commission File Number: 333-39203
   September 30, 2000


                            MARINE BANCSHARES, INC.
                            -----------------------
       (Exact name of small business issuer as specified in its charter)


             Florida                                             65-0729764
             -------                                             ----------
(State or other jurisdiction of                              (I.R.S. Employer
 incorporation or organization)                             Identification No.)


2325 Vanderbilt Beach Road, Naples, Florida                         34109
-------------------------------------------                         -----
 (Address of principal executive offices)                        (Zip Code)


Issuer's telephone number:     (941) 593-6300
                               --------------


                                Not Applicable
                                --------------
             (Former name, former address and former fiscal year,
                         if changed since last report)


Check whether the issuer (1) filed all reports required to be filed by Section
13 or 15(d) of the Securities Exchange Act of 1934 during the past 12 months
(or for such shorter period that the registrant was required to file such
reports), and (2) has been subject to such filing requirements for the past 90
days.

                     Yes [X]                         No [ ]



State the number of shares outstanding of each of the issuer's classes of
common equity, as of the latest practicable date:

Common Stock, $.01 Par Value                            1,150,000
----------------------------               ------------------------------------
            Class                          Outstanding as of September 30, 2000


Transitional Small Business Disclosure Format:

                     Yes [ ]                         No [X]




===============================================================================

<PAGE>   2

                        SAFE HARBOR STATEMENT UNDER THE
                PRIVATE SECURITIES LITIGATION REFORM ACT OF 1995

         Certain statements in this Quarterly Report on Form 10-QSB constitute
"forward-looking statements" within the meaning of the Private Securities
Litigation Reform Act of 1995, such as statements relating to the financial
condition and prospects, lending risks, plans for future business development
and marketing activities, capital spending and financing sources, capital
structure, the effects of regulation and competition, and the prospective
business of both the Company and the Bank. Where used in this Quarterly Report,
the words "anticipate," "believe," "estimate," "expect," "intend," and similar
words and expressions, as they relate to the Company or the Bank or their
respective managements, identify forward-looking statements. Such
forward-looking statements reflect the current views of the Company and are
based on information currently available to the management of the Company and
the Bank and upon current expectations, estimates, and projections about the
Company and its industry, management's beliefs with respect thereto, and
certain assumptions made by management. These forward-looking statements are
not guarantees of future performance and are subject to risks, uncertainties,
and other factors which could cause actual results to differ materially from
those expressed or implied by such forward-looking statements. Potential risks
and uncertainties include, but are not limited to: (i) significant increases in
competitive pressure in the banking and financial services industries; (ii)
changes in the interest rate environment which could reduce anticipated or
actual margins; (iii) changes in political conditions or the legislative or
regulatory environment; (iv) general economic conditions, either nationally or
regionally (especially in southwest Florida), becoming less favorable than
expected resulting in, among other things, a deterioration in credit quality;
(v) changes occurring in business conditions and inflation; (vi) changes in
technology; (vii) changes in monetary and tax policies; (viii) changes in the
securities markets; and (ix) other risks and uncertainties detailed from time
to time in the filings of the Company with the Commission.




<PAGE>   3

PART 1-FINANCIAL INFORMATION
Item 1.  Financial Statements

                          CONSOLIDATED BALANCE SHEETS

                     MARINE BANCSHARES, INC. AND SUBSIDIARY

<TABLE>
<CAPTION>

                                                                September 30,      December 31,
                                                                    2000               1999
                                                                ------------       ------------
ASSETS                                                           (Unaudited)
<S>                                                             <C>                <C>

Cash and due from banks                                         $  1,526,697       $  1,013,048
Federal funds sold and securities purchased
   under agreements to resell                                     10,006,120          6,153,000
                                                                ------------       ------------
                      TOTAL CASH AND CASH EQUIVALENTS             11,532,817          7,166,048
                                                                ------------       ------------

Securities available for sale                                     24,577,243         29,873,893

Loans                                                             25,667,296          3,337,878
Less:
   Allowance for loan losses                                        (133,000)           (49,500)
                                                                ------------       ------------
                      NET LOANS                                   25,534,296          3,288,378
                                                                ------------       ------------

Restricted securities, Federal Reserve Bank and
   Federal Home Loan Bank stock, at cost                             470,000            270,000

Premises and equipment, net of depreciation                        4,520,722          1,038,716

Accrued interest receivable                                          370,427            270,900

Other assets                                                         219,885            301,386
                                                                ------------       ------------
                                                                $ 67,225,390       $ 42,209,321
                                                                ============       ============

LIABILITIES AND STOCKHOLDERS' EQUITY

Deposits
   Non interest-bearing                                         $  1,706,317       $    704,443
   Interest-bearing                                               50,946,849         31,485,726
                                                                ------------       ------------
                                                                  52,653,166         32,190,169

Securities sold under agreements to repurchase                     1,205,796            390,223

Advances from the Federal Home Loan Bank                           4,000,000                 --

Accrued interest payable                                           1,130,006            143,928

Accrued expenses and other liabilities                               142,892            265,298
                                                                ------------       ------------
                      TOTAL LIABILITIES                           59,131,860         32,989,618
                                                                ------------       ------------



Stockholders' Equity (Deficit)
   Preferred stock, par value $.01 per share,
   2,000,000 shares authorized, no shares issued                          --                 --

   Common stock, par value $.01 per share,
      10,000,000 shares authorized,
      1,150,000 issued and outstanding                                11,500             11,500
   Additional paid-in capital                                     10,831,123         10,831,123
   Accumulated deficit                                            (2,695,236)        (1,488,153)
   Accumulated other comprehensive loss                              (53,857)          (134,767)
                                                                ------------       ------------
                      TOTAL STOCKHOLDERS' EQUITY (DEFICIT)         8,093,530          9,219,703
                                                                ------------       ------------
                                                                $ 67,225,390       $ 42,209,321
                                                                ============       ============
</TABLE>


See accompanying notes to financial statements

<PAGE>   4


                            MARINE BANCSHARES, INC.
                            STATEMENTS OF OPERATIONS
                                  (Unaudited)

                                                       Three months ended
                                                          September 30,
                                                   ---------------------------
                                                       2000             1999
                                                   -----------     -----------

Interest income:
     Interest and fees on loans                    $   506,244     $        --
     Interest on securities                            419,624              --
     Interest on federal funds sold                    148,323         121,124
     Interest on reverse repurchase agreement               --              --
     Interest other                                         --             129
                                                   -----------     -----------

Total interest income                                1,074,191         121,253
Interest expense:
     Interest on deposits                              765,313              --
     Interest on repurchase agreements                  15,265              --
     Interest on Federal Home Loan Bank advances        70,914              --
                                                   -----------     -----------
Total Iinterest expense                                851,492              --
                                                   -----------     -----------

Net interest income                                    222,699         121,253

Provision for loan losses                               33,000              --
                                                   -----------     -----------

Net interest income after
     Provision for loan losses                         189,699         121,253

Non-interest income:
     Net realized gain (loss) on sale of
              securities available for sale                 --              --
     Other non-interest income                          11,925             250
                                                   -----------     -----------
Total non-interest income                               11,925             250

Non-interest expense:
     Salaries and benefits                             309,343         138,667
     Occupancy and equipment expense                    87,214          39,210
     Other expense                                     143,093          64,675
                                                   -----------     -----------

Total non-interest expense                             539,650         242,552
                                                   -----------     -----------

Net income (loss)                                     (338,026)       (121,049)
                                                   -----------     -----------

Other comprehensive income (loss)                           --              --
                                                   -----------     -----------

Comprehensive income (loss)                        $  (338,026)    $  (121,049)
                                                   ===========     ===========

Net loss per share                                 $     (0.29)    $     (0.11)
                                                   ===========     ===========

Average shares outstanding                           1,150,000       1,150,000
                                                   ===========     ===========



See accompanying notes to financial statements



<PAGE>   5

                            MARINE BANCSHARES, INC.
                            STATEMENTS OF OPERATIONS
                                  (Unaudited)


                                                           Nine months ended
                                                             September 30,
                                                      -------------------------
                                                          2000           1999
                                                      -----------     ---------

Interest income:
     Interest and fees on loans                       $   849,934     $      --
     Interest on securities                             1,361,388            --
     Interest on federal funds sold                       336,416       298,487
     Interest on reverse repurchase agreement                  --            --
     Interest other                                            --           401
                                                      -----------     ---------

Total interest income                                   2,547,738       298,888

Interest expense:
     Interest on deposits                               1,882,275            --
     Interest on repurchase agreements                     39,784
     Interest on Federal Home Loan Bank  advances         133,921            --
     Interest other                                            --        10,129
                                                      -----------     ---------
Total Iinterest expense                                 2,055,980        10,129
                                                      -----------     ---------

Net interest income                                       491,758       288,759

Provision for loan losses                                  83,500            --
                                                      -----------     ---------

Net interest income after
     provision for loan losses                            408,258       288,759

Non-interest income:
     Net realized gain (loss) on sale of securities
                available for sale                        (52,107)           --
     Other non-interest income                             69,768           250
                                                      -----------     ---------
Total non-interest income                                  17,661           250

Non-interest expense:
     Salaries and benefits                                803,706       256,876
     Occupancy and equipment expense                      284,002        46,111
     Other expense                                        545,292       131,499
                                                      -----------     ---------

Total non-interest expense                              1,633,000       434,486
                                                      -----------     ---------

Net loss                                               (1,207,081)     (145,477)
                                                      -----------     ---------

Other comprehensive income (loss)                              --            --
                                                      -----------     ---------

Comprehensive income (loss)                           $(1,207,081)    $(145,477)
                                                      ===========     =========

Net loss per share                                    $     (1.05)    $   (0.15)
                                                      ===========     =========

Average shares outstanding                              1,150,000       976,669
                                                      ===========     =========



See accompanying notes to financial statements


<PAGE>   6

                            MARINE BANCSHARES, INC.
                            STATEMENTS OF CASH FLOWS
                                  (Unaudited)

<TABLE>
<CAPTION>

                                                                  Three months ended
                                                                     September 30,
                                                             ----------------------------
                                                                 2000            1999
                                                             ------------     -----------
<S>                                                          <C>              <C>

Cash flows from operating activities:
     Net (loss)                                              $   (338,026)    $  (121,049)
     Adjustments to reconcile net income loss to net
         cash used in operating activities:
         Depreciation                                              62,022             506
         Net accretion on securities available for sale           (53,399)
         Provision for loan losses                                 33,000              --
         (Increase) Decrease in accrued interest
            receivable and other assets                           (40,516)         (3,710)
         Increase (Decrease) in accrued interest
            payable and other liabilities                         430,249          47,096
                                                             ------------     -----------

     Total adjustments                                            431,356          43,892
                                                             ------------     -----------

Net cash provided by (used in) operating activities                93,330         (77,157)
                                                             ------------     -----------

Cash flow from investing activities:
     Net increase in loans                                    (11,845,318)             --
     Maturity of securities available for sale                    568,343              --
     Purchase of premises and equipment                           (29,287)       (486,419)
                                                             ------------     -----------
Net cash used in investing activities                         (11,306,262)       (486,419)
                                                             ------------     -----------

Cash flow from financing activities:
     Net increase in deposits                                  11,661,292              --
     Increase in customer repurchase agreements                   287,317              --
                                                             ------------     -----------
Net cash provided by financing activities                      11,948,609              --
                                                             ------------     -----------

Increase (Decrease) in cash and cash equivalents                  735,677        (563,576)

Cash and cash equivalents, beginning of period                 10,797,140       9,786,968
                                                             ------------     -----------

Cash and cash equivalents, end of period                     $ 11,532,817     $ 9,223,392
                                                             ============     ===========

Supplemental disclosure of cash flow information:
     Cash paid during the period for interest                $    421,485     $        --
                                                             ============     ===========
</TABLE>



See accompanying notes to financial statements


<PAGE>   7


                            MARINE BANCSHARES, INC.
                            STATEMENTS OF CASH FLOWS
                                  (Unaudited)

<TABLE>
<CAPTION>

                                                                    Nine months ended
                                                                      September 30,
                                                             -----------------------------
                                                                  2000            1999
                                                             ------------     ------------
<S>                                                          <C>              <C>

Cash flows from operating activities:
     Net (loss)                                              $ (1,207,081)    $   (145,477)
     Adjustments to reconcile net loss)to net
         cash provided by (used in) operating activities:
         Depreciation                                             168,889            2,526
         Net accretion on securities available for sale          (171,097)
         Provision for loan losses                                 83,500               --
         Decrease in deferred
             offering costs                                            --          199,718
         (Increase) Decrease in accrued interest
            and other assets                                      (72,822)         (24,224)
         Increase (Decrease) in accrued interest
            and other liabilities                                 863,672           (2,944)
                                                             ------------     ------------

     Total adjustments                                            872,142          175,076
                                                             ------------     ------------

Net cash provided by (used in) operating activities              (334,939)          29,599
                                                             ------------     ------------

Cash flow from investing activities:
     Net increase in loans                                    (22,329,418)              --
     Sale of securities available for sale                      4,112,653
     Purchase of securities available for sale                 (1,021,024)              --
     Maturity of securities available for sale                  2,311,822               --
     Purchase of premises and equipment                        (3,650,895)        (762,834)
                                                             ------------     ------------
Net cash used in investing activities                         (20,576,862)        (762,834)
                                                             ------------     ------------

Cash flow from financing activities:
     Net proceeds from sale of common stock                            --       10,842,523
     Net increase in deposits                                  20,462,997               --
     Advances from the Federal Home Loan Bank                   4,000,000               --
     Payments on loans payable                                         --         (845,000)
     Increase in customer repurchase agreements                   815,573               --
     Repayment of organizers advances                                  --          (50,000)
                                                             ------------     ------------
Net cash provided by financing activities                      25,278,570        9,947,523
                                                             ------------     ------------

Increase in cash and cash equivalents                           4,366,769        9,214,288

Cash and cash equivalents, beginning of period                  7,166,048            9,104
                                                             ------------     ------------

Cash and cash equivalents, end of period                     $ 11,532,817     $  9,223,392
                                                             ============     ============

Supplemental disclosure of cash flow information:
     Cash paid during the period for interest                $  1,069,902     $     94,108
                                                             ============     ============
</TABLE>



See accompanying notes to financial statements



<PAGE>   8



                     MARINE BANCSHARES, INC. AND SUBSIDIARY
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                 NINE MONTHS ENDED SEPTEMBER 30, 2000 AND 1999


NOTE A - ORGANIZATION AND BASIS OF PRESENTATION

Organization:

         Marine Bancshares, Inc. (the "Company") was incorporated under the
laws of the state of Florida on January 23, 1997. The Company's activities
prior to October 12, 1999 were limited to the organization of its subsidiary,
Marine National Bank of Naples (the "Bank"), and preparation for its initial
public offering of $11,500,000 in common stock. The common stock offering was
completed in February 1999 and the Bank opened for business on October 12,
1999. Of the proceeds from the stock offering, $9.0 million was invested in the
Bank to provide capital for its operation as an FDIC insured commercial bank.


Basis of Presentation:

         The accompanying unaudited consolidated financial statements include
the accounts of the Company and, since it's opening on October 12, 1999, the
Bank. Intercompany accounts and transactions have been eliminated in
consolidation.

         The accompanying consolidated financial statements have been prepared
in accordance with generally accepted accounting principles for interim
financial statements and in accordance with the instructions to Form 10-QSB.
Accordingly, they do not include all of the information and footnotes required
by generally accepted accounting principles for complete financial statements.
In the opinion of management, all adjustments (consisting of normal recurring
accruals) considered necessary for the fair presentation of the Company's
consolidated financial position and results of operations have been made.
Operating results for the three-month and nine-month periods ended September
30, 2000 are not necessarily indicative of the results that may be expected for
the year ending December 31, 2000.




<PAGE>   9

ITEM 2.  MANAGEMENT'S DISCUSSION AND ANALYSIS OR PLAN OF OPERATION.

         The following discussion of the Company's financial condition and
results of operations should be read in conjunction with the consolidated
financial statements and related notes included elsewhere herein.


GENERAL

Marine Bancshares, Inc. (the "Company") was formed in January 1997, and its
subsidiary, Marine National Bank of Naples (the "Bank"), began operations on
October 12, 1999. The third full quarter of consolidated operations ended
September 30, 2000 and is not comparable to the same quarter of 1999 due to the
significant change in the operations of the Company represented by the opening
of the Bank after that quarter ended.


FINANCIAL CONDITION

The Company raised approximately $10.8 million in capital as a result of its
initial public offering in February of 1999. On October 12, 1999, $9.0 million
of these funds were invested in the Bank to provide capital for operations.
Since opening, the Bank has generated $53 million in deposits.

At September 30, 2000, the Bank had originated $25.7 million in loans and holds
$24.6 million in investment securities available for sale and purchased
$470,000 in stock of the Federal Reserve Bank and the Federal Home Loan Bank,
in accordance with their requirements.


RESULTS OF OPERATIONS

Quarters Ended September 30, 2000 and 1999

Interest income generated during the quarter ended September 30, 2000 was the
result of investments made in loans, investment securities available for sale,
and federal funds sold. Of the total interest income, approximately 53% was due
to earnings on investments and Federal Funds sold. The relatively high level of
investment in securities and Federal Funds was the result of deposit inflows
exceeding loan demand during the period from the opening of the Bank until
September 30, 2000. For the third quarter of 1999, all of the Company's
interest income was the result of investing the proceeds of the initial public
offering before the Bank commenced operations.

Interest expense of $851,492 for the quarter ended September 30, 2000 was
primarily related to interest paid on deposits ($765 thousand) and advances
from the Federal Home Loan Bank of Atlanta ($71 thousand). In the corresponding
quarter of 1999, the Bank had not yet opened for business, and there were no
interest-bearing deposits or advances.

The provision for loan losses totaled $33,000 for the quarter ended September
30, 2000. The Bank is providing a reserve for possible loan losses based on the
amount of performing and non-performing loans. At September 30, 2000, there
were no loans classified as non-performing. At September 30, 1999, the Bank had
not opened for business and there were no loans outstanding and no loan loss
reserve.

Non-interest income of $1,925 for the quarter ended September 30, 2000
consisted of fees charged by the Bank to loan and deposit customers.

Non-interest expense of $539,650 for the quarter ended September 30, 2000
consisted primarily of occupancy, salary and employee benefits expenses. Since
the Bank did not have facilities, employees or operations during the third
quarter of 1999, these expenses were significantly lower in 1999.

The Company's net loss during the third quarter of 2000 totaled $345,476.
During the Bank's first year of operations, and until the Bank increases its
loan portfolio and generates lower cost deposits, management expects the losses
to continue.



<PAGE>   10

Nine Months Ended September 30, 2000 and 1999

Interest income generated during the nine months ended September 30, 2000 was
the result of investments made in loans, investment securities available for
sale, and federal funds sold. Of the total interest income, approximately 66%
was due to earnings on investments and Federal Funds sold. The relatively high
level of investment in securities and Federal Funds sold was the result of
deposit inflows exceeding loan demand during the period from the opening of the
Bank until September 30, 2000. For the first nine months of 1999, all of the
Company's interest income was the result of investing the proceeds of the
initial public offering before the Bank commenced operations.

Interest expense of $2,046,372 for the nine months ended September 30, 2000 was
primarily related to interest paid on deposits. In the corresponding period
during 1999, the Bank had not yet opened for business, and there were no
interest-bearing deposits.

The provision for loan losses totaled $83,500 for the nine months September 30,
2000. The Bank is providing a reserve for possible loan losses based on the
amount of performing and non-performing loans. At September 30, 2000, there
were no loans classified as non-performing. At September 30, 1999, the Bank had
not opened for business and there were no loans outstanding and no loan loss
reserve.

Non-interest income of $69,768 for the nine months ended September 30, 2000
consisted of fees charged by the Bank to loan and deposit customers. In
addition, the Bank sold securities available for sale at a loss of $52,107 to
provide funds to invest in loans during the second quarter of 2000.

Non-interest expense of $1,633,000 for the nine months ended September 30, 2000
consisted primarily of occupancy, salary and employee benefits expenses. Since
the Bank did not have operations during the first nine months of 1999, these
expenses were significantly lower in 1999.

The net loss during the nine months ended September 30, 2000 totaled
$1,214,531. During the Bank's first year of operations, and until the Bank
increases its loan portfolio and generates lower cost deposits, management
expects the losses to continue.



<PAGE>   11

PART II - OTHER INFORMATION

ITEM 4.  SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS

         There were no matters submitted to a vote of the security holders
during the third quarter of 2000.

ITEM 6.  EXHIBITS AND REPORTS ON FORM 8-K.

   (a)   Exhibits. The following exhibit is filed with this report:

         Exhibit No.                       Description
         -----------        ------------------------------------------

              27            Financial Data Schedule (for SEC use only)


   (b)   Reports on Form 8-K. No report on Form 8-K was filed during the
         quarter ended September 30, 2000.




<PAGE>   12

                                   SIGNATURES

         Pursuant to the requirements of the Securities Exchange Act of 1934,
the Registrant has duly caused this report to be signed on its behalf by the
undersigned thereunto duly authorized.



Dated: November 13, 2000              By: /s/ Richard E. Horne
                                         --------------------------------------
                                         Richard E. Horne
                                         President and Chief Executive Officer



Dated: November 13, 2000              By: /s/ Thomas V. Ogletree
                                         --------------------------------------
                                          Thomas V. Ogletree
                                          Chief Financial Officer (principal
                                          financial and accounting officer)



<PAGE>   13

                                 EXHIBIT INDEX



EXHIBIT        DESCRIPTION
-------        -----------

  27     Financial Data Schedule
            (for SEC use only)