<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
NINE-MONTH PERIOD FROM JANUARY 1, 1998 THROUGH SEPTEMBER 30, 1998 AND IS
QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
       
<S>                             <C>
<PERIOD-TYPE>                   9-MOS
<FISCAL-YEAR-END>                          DEC-31-1998
<PERIOD-START>                             JAN-01-1998
<PERIOD-END>                               SEP-30-1998
<CASH>                                       2,798,962
<INT-BEARING-DEPOSITS>                               0
<FED-FUNDS-SOLD>                             1,940,000
<TRADING-ASSETS>                                     0
<INVESTMENTS-HELD-FOR-SALE>                  8,828,719
<INVESTMENTS-CARRYING>                         180,000
<INVESTMENTS-MARKET>                                 0
<LOANS>                                     15,366,435
<ALLOWANCE>                                   (179,079)
<TOTAL-ASSETS>                              30,879,158
<DEPOSITS>                                  25,004,623
<SHORT-TERM>                                         0
<LIABILITIES-OTHER>                             79,080
<LONG-TERM>                                          0
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                       676,188
<OTHER-SE>                                   5,119,267
<TOTAL-LIABILITIES-AND-EQUITY>              30,879,158
<INTEREST-LOAN>                                722,577
<INTEREST-INVEST>                              435,389
<INTEREST-OTHER>                               102,998
<INTEREST-TOTAL>                             1,260,964
<INTEREST-DEPOSIT>                             569,590
<INTEREST-EXPENSE>                             573,227
<INTEREST-INCOME-NET>                          687,737
<LOAN-LOSSES>                                  133,706
<SECURITIES-GAINS>                                   0
<EXPENSE-OTHER>                              1,076,339
<INCOME-PRETAX>                               (434,896)
<INCOME-PRE-EXTRAORDINARY>                           0
<EXTRAORDINARY>                                      0
<CHANGES>                                       59,920
<NET-INCOME>                                  (494,816)
<EPS-PRIMARY>                                     (.73)
<EPS-DILUTED>                                     (.73)
<YIELD-ACTUAL>                                    4.20
<LOANS-NON>                                          0
<LOANS-PAST>                                         0
<LOANS-TROUBLED>                                     0
<LOANS-PROBLEM>                                      0
<ALLOWANCE-OPEN>                                45,373
<CHARGE-OFFS>                                        0
<RECOVERIES>                                         0
<ALLOWANCE-CLOSE>                              179,079
<ALLOWANCE-DOMESTIC>                                 0
<ALLOWANCE-FOREIGN>                                  0
<ALLOWANCE-UNALLOCATED>                        179,079
        

</TABLE>