<TABLE> <S> <C>

<PAGE>
 
<ARTICLE> 9
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE
CONSOLIDATED FINANCIAL STATEMENTS OF ROCKDALE NATIONAL BANCSHARES, INC. FOR THE
THREE MONTH PERIOD FROM JANUARY 1, 1998 THROUGH MARCH 31, 1998 AND IS QUALIFIED
IN ITS ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
       
<S>                             <C>
<PERIOD-TYPE>                   3-MOS
<FISCAL-YEAR-END>                          DEC-31-1998
<PERIOD-START>                             JAN-01-1998
<PERIOD-END>                               MAR-31-1998
<CASH>                                       2,647,045
<INT-BEARING-DEPOSITS>                               0
<FED-FUNDS-SOLD>                             3,200,000
<TRADING-ASSETS>                                     0
<INVESTMENTS-HELD-FOR-SALE>                 11,632,019
<INVESTMENTS-CARRYING>                         180,000
<INVESTMENTS-MARKET>                                 0
<LOANS>                                      7,605,444
<ALLOWANCE>                                     87,871
<TOTAL-ASSETS>                              27,225,994
<DEPOSITS>                                  21,173,048
<SHORT-TERM>                                         0
<LIABILITIES-OTHER>                             23,333
<LONG-TERM>                                          0
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                       676,188
<OTHER-SE>                                   5,353,425
<TOTAL-LIABILITIES-AND-EQUITY>              27,225,994
<INTEREST-LOAN>                                146,502
<INTEREST-INVEST>                              112,062
<INTEREST-OTHER>                                59,662
<INTEREST-TOTAL>                               318,226
<INTEREST-DEPOSIT>                             169,637
<INTEREST-EXPENSE>                             169,637
<INTEREST-INCOME-NET>                          148,589
<LOAN-LOSSES>                                   42,498
<SECURITIES-GAINS>                                   0
<EXPENSE-OTHER>                                339,700
<INCOME-PRETAX>                               (214,613)
<INCOME-PRE-EXTRAORDINARY>                    (214,613)
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                  (214,613)
<EPS-PRIMARY>                                     (.32)
<EPS-DILUTED>                                     (.32)
<YIELD-ACTUAL>                                    3.26
<LOANS-NON>                                          0
<LOANS-PAST>                                         0
<LOANS-TROUBLED>                                     0
<LOANS-PROBLEM>                                      0
<ALLOWANCE-OPEN>                                     0
<CHARGE-OFFS>                                        0
<RECOVERIES>                                         0
<ALLOWANCE-CLOSE>                                    0
<ALLOWANCE-DOMESTIC>                                 0
<ALLOWANCE-FOREIGN>                                  0
<ALLOWANCE-UNALLOCATED>                              0
        

</TABLE>