<PAGE>   1
                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                             -----------------------
                                    FORM 10-K
                                  ANNUAL REPORT
                             -----------------------
         (Mark One)
         ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
     X   SECURITIES EXCHANGE ACT OF 1934 [FEE REQUIRED]
   -----
   For the fiscal year ended December 31, 1998
                             -----------------
         TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
         SECURITIES EXCHANGE ACT OF 1934 [NO FEE REQUIRED]
   ------
   For the transition period from . . . . . . to . . . . . .
   Commission file number 0-20255
                          -------

                         Mahoning National Bancorp, Inc.
                         -------------------------------
             (Exact name of registrant as specified in its charter)

                    OHIO                                34-1692031
                    ----                                ----------
         (State or other jurisdiction of             (I.R.S. Employer
         incorporation or organization)           Identification Number)

         23 FEDERAL PLAZA, YOUNGSTOWN, OH               44501-0479
         --------------------------------               ----------
         (Address of principal executive offices)       (Zip Code)
                                 (330) 742-7000
                                 --------------
                         (Registrant's telephone number)
         Securities registered pursuant to Section 12(b) of the Act:
                                      NONE
                                      ----
         Securities registered pursuant to Section 12(g) of the Act:
                 COMMON STOCK, NO PAR VALUE, STATED VALUE $1.00
                 ----------------------------------------------
                                (Title of Class)

         Indicate by check mark if disclosure of delinquent filers pursuant to
Item 405 of Regulation S-K is not contained herein, and will not be contained,
to the best of registrant's knowledge, in definitive proxy or information
statements incorporated by reference in Part III of this Form 10-K or any
amendment to this Form 10-K. /X/

         Indicate by check mark whether the registrant (1) has filed all reports
required to be filed by Section 13 or 15(d) of the Securities Exchange Act of
1934 during the preceding 12 months and (2) has been subject to such filing
requirements for the past 90 days.
         Yes  X                          No
             ---                            ---

         The aggregate market value of Common Stock, No Par Value, $1 Stated
Value Per Share, held by non-affiliates on February 28, 1999, was approximately
$170,000,000.

         As of February 28, 1999, there were 6,300,000 shares of Common Stock,
No Par Value, $1 Stated Value Per Share, issued and outstanding.

DOCUMENTS INCORPORATED BY REFERENCE

(1)      Portions of the registrant's Annual Report to Shareholders for the year
         ended December 31, 1998, are incorporated by reference into Parts I,
         II, and IV.

(2)      The Notice of Annual Meeting of Shareholders and Proxy Statement 
         relating to the 1999 Annual Meeting of Shareholders of the Corporation
         on March 16, 1999, is incorporated by reference into Part III.



<PAGE>   2


Mahoning National Bancorp, Inc.
Form 10-K




                                     PART I


ITEM 1. BUSINESS

         Mahoning National Bancorp, Inc. ("the Registrant") was incorporated in
         1992 under the laws of the state of Ohio as a bank holding company.

         The Registrant has one wholly-owned subsidiary, The Mahoning National
         Bank of Youngstown (Mahoning National), which was organized under the
         laws of the State of Ohio in 1868.

         The Registrant has no employees; however, as of December 31, 1998
         Mahoning National employed approximately 375 full-time equivalent
         employees.

         The Registrant and its subsidiary do not have any banking offices in a
         foreign country and with the exception of State of Israel Bonds
         totaling $60 thousand, has no foreign assets, liabilities or related
         income and expense for the years presented.

         A description of the Registrant's business and discussion of operations
         is set forth on pages 19 through 29 of the 1998 Annual Report to
         Shareholders, included in this Form 10-K as Exhibit 13, and is
         incorporated herein by reference.

         The following additional financial information as required under Guide
         3 disclosure is included in this Form 10-K and is incorporated herein
         by reference:

         Items I - Distribution of Assets, Liabilities and Stockholders' Equity;
         Interest Rates and Interest Differential - The information required is
         contained in Management's Discussion and Analysis on pages 20 through
         29 in the 1998 Annual Report to Shareholders, included in this Form
         10-K as Exhibit 13, incorporated herein by reference.



<PAGE>   3

Mahoning National Bancorp, Inc.
Form 10-K

Item II - Investment Portfolio

The carrying values, fair values, average yields and maturity distributions of
all investment securities are summarized in the following table.

<TABLE>
<CAPTION>
                                                   December 31, 1998                    December 31, 1997                
       AVAILABLE FOR SALE:
                                           Carrying      Fair      Average        Carrying       Fair     Average        
       (Amounts in thousands)                Value       Value      Yield*         Value        Value      Yield*        
       --------------------------------------------------------------------    ------------------------------------      
<S>                                         <C>        <C>          <C>           <C>          <C>          <C>          
U.S. Treasury and agencies:
       Within one year                      $ 35,252   $ 35,252     6.00%         $ 4,992      $ 4,992      5.47%        
       After one but within five years       178,363    178,363     5.96%         161,290      161,290      6.14%        
                                         ----------------------------------    ------------------------------------      
                                             213,615    213,615     5.97%         166,282      166,282      6.12%        

Mortgaged-backed securities and 
collateralized mortgage obligations:
       Within one year                         2,753      2,753     6.59%             874          874      9.16%        
       After one but within five years           194        194     9.43%           4,284        4,284      6.78%        
       After five but within ten years           573        573     9.30%               -            -         -         
                                         ----------------------------------    ------------------------------------      
                                               3,520      3,520     7.19%           5,158        5,158      7.18%        

Obligations of states and political 
subdivisions:
       Within one year                         2,345      2,345     4.46%           2,273        2,273      4.67%        
       After one but within five years        17,813     17,813     4.20%          11,813       11,813      4.40%        
       After five but within ten years             -          -        -              500          500      4.30%        
                                         ----------------------------------    ------------------------------------      
                                              20,158     20,158     4.23%          14,586       14,586      4.44%        

Other                                          3,744      3,744                     3,552        3,552                   
                                         -----------------------               ------------------------                  
       Total investment securities         $ 241,037  $ 241,037                 $ 189,578    $ 189,578                   
                                         =======================               ========================                  

<CAPTION>                              
                                                  December 31, 1996             
       AVAILABLE FOR SALE:                                                      
                                          Carrying       Fair        Average    
       (Amounts in thousands)               Value        Value         Yield*   
       ------------------------------------------------------------------------ 
<S>                                       <C>          <C>             <C>      
U.S. Treasury and agencies:                                                     
       Within one year                    $ 25,045     $ 25,045        6.85%    
       After one but within five years      99,906       99,906        6.11%    
                                       ---------------------------------------- 
                                           124,951      124,951        6.26%    
                                                                                
Mortgaged-backed securities and                                                 
collateralized mortgage obligations:                                            
       Within one year                           -            -          -      
       After one but within five years       5,009        5,009        7.14%    
       After five but within ten years         393          393        9.36%    
                                       ---------------------------------------- 
                                             5,402        5,402        7.30%    
                                                                                
Obligations of states and political                                             
subdivisions:                                                                   
       Within one year                       1,543        1,543        4.64%    
       After one but within five years       8,205        8,205        4.48%    
       After five but within ten years         126          126        4.65%    
                                       ---------------------------------------- 
                                             9,874        9,874        4.51%    
                                                                                
Other                                        3,373        3,373                 
                                       -------------------------                
       Total investment securities       $ 143,600    $ 143,600                 
                                       =========================                
</TABLE>


<TABLE>
<CAPTION>
                                                       December 31, 1998                    December 31, 1997           
       HELD TO MATURITY:
                                            Carrying      Fair       Average        Carrying      Fair       Average    
       (Amounts in thousands)                 Value       Value       Yield*         Value       Value       Yield*     
       ----------------------------------------------------------------------     -----------------------------------   
<S>                                          <C>         <C>           <C>          <C>         <C>           <C>       
U.S. Treasury and agencies:
       Within one year                       $ 14,998    $ 14,998      5.40%        $ 35,942    $ 35,938      5.77%     
       After one but within five years              -           -         -           14,982      14,937      5.40%     
                                          -----------------------------------     -----------------------------------   
                                               14,998      14,998      5.40%          50,924      50,875      5.66%     


Obligations of states and political 
subdivisions:
       Within one year                          2,624       2,646      4.47%           1,339       1,347      4.46%     
       After one but within five years          6,228       6,332      4.41%           8,855       8,966      4.43%     
                                          -----------------------------------     ----------------------------------    
                                                8,852       8,978      4.43%          10,194      10,313      4.43%     

Other                                              60          60                         60          60                
                                          ------------------------                -----------------------               
       Total investment securities           $ 23,910    $ 24,036                   $ 61,178    $ 61,248                
                                          ========================                =======================               

<CAPTION>                               
                                                      December 31, 1996         
       HELD TO MATURITY:                                                        
                                             Carrying       Fair        Average 
       (Amounts in thousands)                 Value        Value        Yield*  
       ---------------------------------  ------------------------------------- 
<S>                                          <C>          <C>            <C>    
U.S. Treasury and agencies:                                                     
       Within one year                       $ 23,549     $ 23,573       5.94%  
       After one but within five years         50,785       50,599       5.66%  
                                          ------------------------------------- 
                                               74,334       74,172       5.75%  
                                                                                
                                                                                
Obligations of states and political                                             
subdivisions:                                                                   
       Within one year                          1,142        1,143       3.66%  
       After one but within five years         10,196       10,271       4.43%  
                                          ------------------------------------- 
                                               11,338       11,414       4.35%  
                                                                                
Other                                              60           60              
                                          -------------------------             
       Total investment securities           $ 85,732     $ 85,646              
                                          =========================             
</TABLE>


       * Yields on tax exempt securities have not been calculated on a tax 
         equivalent basis.



<PAGE>   4



Mahoning National Bancorp, Inc.
Form 10-K


         Item III - Loan Portfolio - The information required is contained in
         Management's Discussion and Analysis on pages 20 through 23 in the 1998
         Annual Report to Shareholders, included in this Form 10-K as Exhibit
         13, incorporated herein by reference. Potential problem loans at
         December 31, 1998, that were not disclosed as nonaccrual, accruing
         loans 90 days or more past due or troubled debt restructurings totaled
         $3.528 million. These loans represent borrowers with possible credit
         problems that may effect the ability of the borrowers to comply with
         the present loan repayment terms and result in the disclosure of such
         loans pursuant to Item III. C.1. All interest bearing assets have been
         disclosed as required under Item III. C.1. or 2.


         Item IV - Summary of Loan Loss Experience - The information required is
         contained in Management's Discussion and Analysis on pages 22 and 23 in
         the 1998 Annual Report to Shareholders, included in this Form 10-K as
         Exhibit 13, incorporated herein by reference.


         Item V - Deposits - The information required is contained in
         Management's Discussion and Analysis on pages 24 and 28 in the 1998
         Annual Report to Shareholders, included in this Form 10-K as Exhibit
         13, incorporated herein by reference.

         Item VI - Return on Equity and Assets - The information required can be
         found on page 18 of the 1998 Annual Report to Shareholders, included in
         this Form 10-K as Exhibit 13, incorporated herein by reference. In
         addition, the average equity to average asset ratio for the previous
         five years was as follows:

<TABLE>
<S>                                         <C>
                          1998     -        11.51%
                          1997     -        10.56%
                          1996     -         9.78%
                          1995     -         9.14%
                          1994     -         8.67%
</TABLE>


         Item VII - Short Term Borrowing - The information required can be found
         on page 1 Consolidated Statements of Financial Condition, for year end
         balances, and on page 9, Note G - Short Term Borrowings, of the 1998
         Annual Report to Shareholders, included in this Form 10-K as Exhibit
         13, incorporated herein by reference.

         Listed below are the names, ages, positions held and terms in office
         for the Registrant's executive officers and their positions held with
         the sole subsidiary, The Mahoning National Bank of Youngstown. The
         executive officers of the Registrant and the subsidiary serve at the
         direction of the Board of Directors, and are elected annually by the
         Board of Directors of the appropriate entity.

         Gregory L. Ridler
                  Age - 52

                  Current Positions - Chairman of the Board, President and Chief
                  Executive Officer of Mahoning National Bancorp, Inc. (1992).
                  President and Chief Executive Officer of Mahoning National
                  Bank (1989).



<PAGE>   5



Mahoning National Bancorp, Inc.
Form 10-K


Norman E. Benden, Jr.
                  Age - 40


                  Current Positions - Secretary and Treasurer for Mahoning
                  National Bancorp, Inc. (1998). Senior Vice President and Chief
                  Financial Officer of Mahoning National Bank(1996).

                  Previous five year experience - Treasurer for Mahoning
                  National Bancorp, Inc. (1992) Senior Vice President and
                  Comptroller of Mahoning National Bank (1994).

ITEM 2. PROPERTIES

         The main office of the Registrant and its sole subsidiary, Mahoning
         National, is a thirteen-story office building located at 23 Federal
         Plaza in Youngstown, Ohio. Mahoning National owns both the land and the
         building at this location. The Registrant and Mahoning National occupy,
         and use for banking business 81,521 square feet of the approximately
         182,000 square feet of usable space. The remainder of the building is
         leased to business and professional tenants.

         The Campbell branch office of Mahoning National is located at 809
         McCartney Road, Campbell, Ohio. This 3,600 square foot office is used
         strictly for banking services. Mahoning National owns both the land and
         building at this location.

         The South and Midlothian branch of Mahoning National is located at 525
         E. Midlothian, Youngstown, Ohio. This 3,400 square foot office is used
         strictly for banking services. Mahoning National owns both the land and
         building at this location.

         The Kinsman branch office of Mahoning National is located at 8222 Main
         Street, Kinsman, Ohio. This 4,680 square foot office is used strictly
         for banking services. Mahoning National owns both the land and building
         at this location.

         The Brookfield branch office of Mahoning National is located at 579
         Bedford Road, Brookfield, Ohio. This 3,700 square foot office is used
         strictly for banking services. Mahoning National owns both the land and
         the building at this location.

         The South & 224 branch office of Mahoning National, a 3,460 square foot
         office located at 7235 South Avenue, Youngstown, Ohio is used strictly
         for banking services. Mahoning National owns the building but leases
         the land at this location. The lease on the land at South & 224 expires
         on 05/31/04 with two 5 year options.

         The Boardman branch office of Mahoning National is located at 711
         Boardman-Canfield Road, Boardman, Ohio. This 3,500 square foot office
         is used strictly for banking services. Mahoning National owns both the
         land and building at this location.

         The Canfield branch office of Mahoning National is located at 11 Manor
         Hill Drive, Canfield, Ohio. This 3,100 square foot office is used
         strictly for banking services. Mahoning National owns both the land and
         building at this location.

         The Austintown branch office of Mahoning National Bank located at 6010
         Mahoning Avenue was constructed in the fourth quarter of 1998. This
         3,600 square foot office is used strictly for banking services.
         Mahoning National owns both the land and building at this location. In
         January 1999, the Company consolidated its Jackson Milton and Wedgewood
         branch offices into the Austintown branch office.

<PAGE>   6


Mahoning National Bancorp, Inc.
Form 10-K


         The Registrant's subsidiary, Mahoning National maintains an additional
         twelve banking offices which are located in Mahoning and Trumbull
         Counties in northeastern Ohio. All of these locations are leased and
         used strictly for banking services.

         All of the properties owned or leased by the Registrant's subsidiary
         are considered by management to be suitable and adequate for current
         operations.

ITEM 3.  LEGAL PROCEEDINGS

         There is no pending material litigation, other than the ordinary
         routine litigation incidental to the business, to which the Registrant
         or its subsidiary is a party to or of which any property is subject to.
         Further, there are no material proceedings to which any director,
         officer or affiliate of the Registrant, or any associate of any such
         director, officer or affiliate is a party adverse to the Registrant or
         its subsidiary.


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

         No matter was submitted to a vote of security holders of the Registrant
         during the fourth quarter of 1998.



                                     PART II

ITEM 5.  MARKET FOR THE REGISTRANT'S COMMON STOCK AND RELATED STOCKHOLDER 
         MATTERS


         Market Information:

         Effective January 5, 1998, the Company's common shares were listed on
         The Nasdaq Stock Market under the symbol "MGNB". Currently the
         following four brokerage firms serve as market makers for the Company's
         common stock: McDonald & Company Securities, Inc., Sandler O'Neill &
         Partners, L.P., F. J. Morrissey & Co., Inc. and Everen Securities, Inc.
         The following table lists the high and low sales prices as reported by
         The Nasdaq Stock Market for 1998. Prior to January 5, 1998, the
         Company's common shares were traded Over-the-Counter, generally in the
         Youngstown area. The price information reported for 1997 reflects the
         high and low bid prices for the year and does not necessarily reflect
         prices in actual transactions.


<TABLE>
<CAPTION>
         Quarter                                 1998                      1997
                                                 ----                      ----
                                             High     Low               High     Low
                                             ----     ---               ----     ---
<S>                                         <C>      <C>               <C>      <C>
         1st                                $39.00   $26.00            $22.75   $21.50
         2nd                                 45.50    34.25             22.50    21.50
         3rd                                 44.00    32.00             26.25    22.50
         4th                                 34.50    28.25             33.00    26.00
</TABLE>


         For additional information on the Company's common stock and related
         stockholder matters refer to Note-L on pages 11 and 12 of the 1998
         Annual Report to Shareholders, included in this Form 10-K as Exhibit
         13, incorporated herein by reference.

<PAGE>   7



Mahoning National Bancorp, Inc.
Form 10-K


         Holders of Registrant's Stock:

         At the close of business on January 31, 1999 there were approximately
         1,544 stockholders of record of Mahoning National Bancorp, Inc. common
         stock.


         Dividend Information:

         The following table lists the frequency and amount of cash dividends
         declared in the past two years. While the Company expects comparable
         cash dividends will be paid in the future, they will be dependent upon
         earnings, financial condition of the Company and other business
         factors.

<TABLE>
<CAPTION>
         Quarter
                                    1998                       1997
                                    ----                       ----
<S>                                 <C>                       <C>  
         1st                        $0.21                     $0.16
         2nd                         0.21                      0.16
         3rd                         0.21                      0.16
         4th                         0.26                      0.21
</TABLE>


         The dividend payout ratio of the Registrant for the past five years was
         as follows:

<TABLE>
<S>                                                <C>   
                                            1998 = 40.45%
                                            1997 = 33.59%
                                            1996 = 30.66%
                                            1995 = 29.09%
                                            1994 = 29.07%
</TABLE>



ITEM 6. SELECTED FINANCIAL DATA

         The selected financial data for each of the five years in the period
         ending December 31, 1998 can be found on page 18 in the 1998 Annual
         Report to Shareholders, included in this Form 10-K as Exhibit 13,
         incorporated herein by reference.


ITEM 7. MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS 
        OF OPERATIONS

         This information is contained on pages 20 through 29 in the 1998 Annual
         Report to Shareholders, included in this Form 10-K as Exhibit 13,
         incorporated herein by reference.


ITEM 7A. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

         This information is contained on pages 28 and 29 in the 1998 Annual
         Report to Shareholders, included in this Form 10-K as Exhibit 13,
         incorporated herein by reference.


ITEM 8. FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA

         The Consolidated Financial Statements, Notes to Consolidated Financial
         Statements, and the Report of Independent Auditors can be found on
         pages 1 through 16 of the 1998 Annual Report to Shareholders, included
         in this Form 10-K as Exhibit 13, incorporated herein by reference.


<PAGE>   8



Mahoning National Bancorp, Inc.
Form 10-K


ITEM 9. CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND 
        FINANCIAL DISCLOSURE

         Not Applicable.


                                    PART III

ITEM 10. DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT

         The information set forth under the caption "Election of Directors and
         Information with Respect to Directors and Officers" on pages 2 and 3 of
         the Notice of Annual Meeting and Proxy Statement, included in this Form
         10-K as Exhibit 99(a), is incorporated herein by reference.

         The executive officers of the Registrant are listed under Item 1 of
         this document.

         Compliance with Section 16(a) of the Securities Exchange Act of 1934.

                  The information pertaining to compliance with Section 16(a) of
                  the Securities Exchange Act of 1934 can be found on page 11 of
                  the Notice of Annual Meeting and Proxy Statement, included in
                  this Form 10-K as Exhibit 99(a), incorporated herein by
                  reference.

ITEM 11. EXECUTIVE COMPENSATION

         The information pertaining to executive compensation can be found on
         pages 6 through 10 of the Notice of Annual Meeting and Proxy Statement,
         included in this Form 10-K as Exhibit 99(a), incorporated herein by
         reference.

ITEM 12. SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT

         (a)      Security ownership of certain beneficial owners.
                  None

         (b)      Security ownership of management.


                  The information pertaining to security ownership of management
                  can be found on page 4 of the Notice of Annual Meeting and
                  Proxy Statement, included in this Form 10-K as Exhibit 99(a),
                  incorporated herein by reference.

                  The following details the security ownership of the executive
                  officers of the Registrant:

                  Norman E. Benden, Jr. - 3,482 shares of common stock
                                          (.055% of class)

         (c)      Changes in control.
                  There are no contracts or arrangements known to the
                  Registrant, that at a subsequent date, could result in a
                  change in control of the Registrant.



<PAGE>   9


Mahoning National Bancorp, Inc.
Form 10-K



ITEM 13. CERTAIN RELATIONSHIPS AND RELATED TRANSACTION

         The information pertaining to certain relationships and related
         transactions can be found under the caption "Transactions with
         Management" on page 11 of the Notice of Annual Meeting and Proxy
         Statement, included in this Form 10-K as Exhibit 99(a), incorporated
         herein by reference.

                                     PART IV

ITEM 14. EXHIBITS, FINANCIAL STATEMENT SCHEDULES AND REPORTS ON FORM 8-K

         (a)  1.  Financial Statements:
                  The following consolidated financial statements of the
                  Registrant appear on pages 1 through 16 of the Registrant's
                  1998 Annual Report to Shareholders, Exhibit 13 to this Form
                  10-K, and are incorporated herein by reference:
                             Consolidated Statements of Financial Condition -
                                    December 31, 1998 and 1997
                             Consolidated Statements of Income -
                                    Three years ended December 31, 1998
                             Consolidated Statements of Changes in
                             Stockholders' Equity -
                                    Three years ended December 31, 1998
                             Consolidated Statements of Cash Flows -
                                    Three years ended December 31, 1998
                             Notes to Consolidated Financial Statements
                             Report of Independent Auditors


              2.  Financial Statement Schedules:
                  Schedules normally required of Form 10-K are omitted since the
                  required information is not applicable, not deemed material or
                  is shown in the respective consolidated financial statements
                  or notes thereto.


         (b)  1.  Reports on Form 8-K:
                  No reports on Form 8-K were filed by the Registrant during the
                  fourth quarter of 1998.


         (c)  1.  Exhibits:

                         (2)  Plan of Acquisition, Reorganization, Arrangement,
                              Liquidation or Succession. Not applicable.

                         (3a) The Articles of Incorporation of Mahoning National
                              Bancorp, Inc., filed on the Registrant's Form S-4,
                              File # 33-45045 effective February 11, 1992, in
                              addition Form 8-K, dated March 21, 1995,
                              Certificate of Amendment by Shareholders to the
                              Articles of Incorporation of Mahoning National
                              Bancorp, Inc., and Form 8-K, dated March 19, 1996,
                              Certificate of Amendment by Shareholders to the
                              Articles of Incorporation of Mahoning National
                              Bancorp, Inc., and Amendment of Article Fourth of
                              the Articles of Incorporation of Mahoning National
                              Bancorp, Inc., is incorporated herein by
                              reference.


<PAGE>   10


Mahoning National Bancorp, Inc.
Form 10-K


                         (3b) The Bylaws of Mahoning National Bancorp, Inc.,
                              filed on the Registrant's Form S-4, File #33-45045
                              effective February 11, 1992, is incorporated
                              herein by reference.

                         (4)  Instruments defining the Rights of Security
                              Holders, Including Indentures, filed on the
                              Registrant's Form S-4, File #33-45045 effective
                              February 11, 1992, is incorporated herein by
                              reference.

                         (9)  Voting Trust Agreement
                              Not applicable.

                         (10) Material Contracts:
                         
                              (10a) Change-In-Control Protective Agreement
                                    between Mahoning National Bancorp, Inc., and
                                    Norman E. Benden, Jr. - Secretary and
                                    Treasurer (Mahoning National Bancorp, Inc.),
                                    Senior Vice President and Chief Financial
                                    Officer (Mahoning National Bank of
                                    Youngstown), filed with the Registrant's
                                    Form 10-Q dated June 30, 1997, is
                                    incorporated herein by reference. 

                              (10b) Change-In-Control Protective Agreement
                                    between Mahoning National Bancorp, Inc., and
                                    Gregory L. Ridler - Chairman of the Board,
                                    President and Chief Executive Officer
                                    (Mahoning National Bancorp, Inc.), President
                                    and Chief Executive Officer (Mahoning
                                    National Bank of Youngstown), filed with the
                                    Registrant's Form 10-Q dated June 30, 1997,
                                    is incorporated herein by reference.

                              (10c) Change-In-Control Protective Agreement
                                    between Mahoning National Bancorp, Inc., and
                                    Karen R. DeSalvo - Vice President -
                                    Marketing (Mahoning National Bank of
                                    Youngstown), filed with the Registrant's
                                    Form 10-Q dated June 30, 1997, is
                                    incorporated herein by reference.

                              (10d) Change-In-Control Protective Agreement
                                    between Mahoning National Bancorp, Inc., and
                                    Martha Drabiski - Vice President, Auditor
                                    and Compliance Officer (Mahoning National
                                    Bank of Youngstown), filed with the
                                    Registrant's Form 10-Q dated September 30,
                                    1998 is incorporated herein by reference.

                              (10e) Change-In-Control Protective Agreement
                                    between Mahoning National Bancorp, Inc., and
                                    Frank Hierro - Senior Vice President
                                    (Mahoning National Bank of Youngstown),
                                    filed with the Registrant's Form 10-Q dated
                                    June 30, 1997, is incorporated herein by
                                    reference.

                              (10f) Change-In-Control Protective Agreement
                                    between Mahoning National Bancorp, Inc., and
                                    Dexter Hollen - Vice President


<PAGE>   11


Mahoning National Bancorp, Inc.
Form 10-K


                                    (Mahoning National Bank of Youngstown), 
                                    filed with the Registrant's Form 10-Q dated 
                                    June 30, 1997, is incorporated herein by 
                                    reference.

                              (10g) Change-In-Control Protective Agreement
                                    between Mahoning National Bancorp, Inc., and
                                    John R. Lewis - Senior Vice President
                                    (Mahoning National Bank of Youngstown),
                                    filed with the Registrant's Form 10-Q dated
                                    June 30, 1997, is incorporated herein by
                                    reference.

                              (10h) Change-In-Control Protective Agreement
                                    between Mahoning National Bancorp, Inc., and
                                    J. David Sabine - Senior Vice President and
                                    Senior Trust Officer (Mahoning National Bank
                                    of Youngstown), filed with the Registrant's
                                    Form 10-Q dated June 30, 1997, is
                                    incorporated herein by reference.

                              (10i) Change-In-Control Protective Agreement
                                    between Mahoning National Bancorp, Inc., and
                                    David E. Westerburg - Senior Vice President
                                    (Mahoning National Bank of Youngstown),
                                    filed with the Registrant's Form 10-Q dated
                                    June 30, 1997, is incorporated herein by
                                    reference.

                              (10j) Change-In-Control Protective Agreement
                                    between Mahoning National Bancorp, Inc., and
                                    Donna J. Mowrey - Vice President Human
                                    Resources (Mahoning National Bank of
                                    Youngstown), filed with the Registrant's
                                    Form 10-K dated December 31, 1997, is
                                    incorporated herein by reference.

                              (10k) Supplemental Executive Retirement Plan
                                    between Mahoning National Bank of Youngstown
                                    and Gregory L. Ridler, originally filed with
                                    the Registrant's Form 10-K dated December
                                    31, 1995, was amended and refiled with the
                                    Registrant's Form 10-Q dated June 30, 1997,
                                    and is incorporated herein by reference.

                              (10l) Split Dollar Life Insurance Plan between
                                    Mahoning National Bank and Gregory L. Ridler
                                    filed with the Registrant's Form 10-Q dated
                                    June 30, 1997, is incorporated herein by
                                    reference.

                              (10m) Executive Phantom Stock Bonus Plan, as
                                    amended December 14, 1998, between The
                                    Mahoning National Bank of Youngstown and
                                    Norman E. Benden, Jr., included in this form
                                    as Exhibit 10(m), is incorporated herein by
                                    reference.

                              (10n) Executive Phantom Stock Bonus Plan, as
                                    amended December 14, 1998, between The

<PAGE>   12


Mahoning National Bancorp, Inc.
Form 10-K


                                    Mahoning National Bank of Youngstown and 
                                    Frank Hierro, included in this form as 
                                    Exhibit 10(n), is incorporated herein by 
                                    reference.

                              (10o) Executive Phantom Stock Bonus Plan, as
                                    amended December 14, 1998, between The
                                    Mahoning National Bank of Youngstown and
                                    Gregory L. Ridler, included in this form as
                                    Exhibit 10(o), is incorporated herein by
                                    reference.

                              (10p) Executive Phantom Stock Bonus Plan, as
                                    amended December 14, 1998, between The
                                    Mahoning National Bank of Youngstown and
                                    David E. Westerburg, included in this form
                                    as Exhibit 10(p), is incorporated herein by
                                    reference.

                              (10q) Executive Deferred Cash Bonus Plan between
                                    The Mahoning National Bank of Youngstown and
                                    Parker T. McHenry, filed with the
                                    Registrant's Form 10-Q dated September 30,
                                    1997, is incorporated herein by reference.

                              (11)  Statement Regarding Computation of Per Share
                                    Earnings.

                                    The necessary information can be found under
                                    Note A-12 of the Notes to Consolidated
                                    Financial Statements on page 6 of the 1998
                                    Annual Report to Shareholders, included in
                                    this Form 10-K as Exhibit 13, incorporated
                                    herein by reference.

                              (12)  Statement Regarding Computation of Ratios.
                                    Not applicable.

                              (13)  1998 Annual Report to Shareholders.

                              (16)  Letter Regarding Change in Certifying
                                    Accountant. Not applicable.

                              (18)  Letter Regarding Change in Accounting
                                    Principles Not applicable.

                              (21)  Subsidiaries of the Registrant.

                              (22)  Published Report Regarding Matters Submitted
                                    to Vote of Security Holders. Not applicable.

                              (23)  Consents of Experts and Counsel. Not
                                    applicable.

                              (24)  Power of Attorney. Not applicable.

<PAGE>   13


Mahoning National Bancorp, Inc.
Form 10-K


                              (27)  Financial Data Schedule.


                              (28)  Information from Reports Furnished to State
                                    Insurance Regulatory Authorities. Not
                                    applicable.

                              (99)  Additional Exhibits.

                                  (a) The Registrant's Notice of Annual Meeting
                                      and Proxy Statement dated March 16, 1999.


<PAGE>   14





                                   SIGNATURES

Pursuant to the requirement of Section 13 or 15(d) 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 on the 16th day of March,
1999.

                  MAHONING NATIONAL BANCORP, INC.
                  (Registrant)





                  /s/ Gregory L. Ridler
                  ------------------------------
                  GREGORY L. RIDLER
                  President
                  (Principal Executive Officer)

Pursuant to the requirements of the Securities Exchange Act of 1934, this report
has been signed below by the following persons on behalf of the Registrant and
in the capacities indicated on the 16th day of March, 1999.






/s/ Norman E. Benden, Jr.                  /s/ Gregory L. Ridler
--------------------------------------     ------------------------------------
Norman E. Benden, Jr. - Secretary and      Gregory L. Ridler
Treasurer (Principal Financial and         Chairman of the Board,
Accounting Officer)                        President and Chief Executive Officer






/s/ William J. Bresnahan                   /s/ Warren P. Williamson, III
--------------------------------------     ------------------------------------
William J. Bresnahan - Director            Warren P. Williamson, III- Director






/s/ Daniel B. Roth                         /s/ Charles J. McCrudden, Jr.
--------------------------------------     ------------------------------------
Daniel B. Roth - Director                  Charles J. McCrudden, Jr.- Director


<PAGE>   15


Mahoning National Bancorp, Inc.
Form 10-K





                                  EXHIBIT INDEX



Exhibit
Number

10(m)    Executive Phantom Stock Bonus Plan (as Amended December 14, 1998)-
         Norman E. Benden, Jr.

10(n)    Executive Phantom Stock Bonus Plan (as Amended December 14, 1998)-
         Frank Hierro


10(o)    Executive Phantom Stock Bonus Plan (as Amended December 14, 1998)-
         Gregory L. Ridler

10(p)    Executive Phantom Stock Bonus Plan (as Amended December 14, 1998)-David
         E. Westerburg

13       1998 Annual Report to Shareholders

21       Subsidiaries of the Registrant

27       Financial Data Schedule

99(a)    Registrant's Notice of Annual Meeting and Proxy Statement dated 
         March 16, 1999