<TABLE> <S> <C>

<PAGE>
 
<ARTICLE> 9
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE
CONSOLIDATED STATEMENT OF CONDITION, THE CONSOLIDATED STATEMENT OF EARNINGS, THE
CONSOLIDATED STATEMENT OF CASH FLOWS, AND TABLES 2, 7 AND 8 OF ITEM 2 OF THE
AMSOUTH BANCORPORATION FORM 10-Q FOR THE QUARTERLY PERIOD ENDED SEPTEMBER 30,
1997 AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH STATEMENTS.
</LEGEND>
<RESTATED> 
<MULTIPLIER> 1,000
       
<S>                             <C>
<PERIOD-TYPE>                   9-MOS
<FISCAL-YEAR-END>                          DEC-31-1997
<PERIOD-START>                             JAN-01-1997
<PERIOD-END>                               SEP-30-1997
<CASH>                                         579,032
<INT-BEARING-DEPOSITS>                               0
<FED-FUNDS-SOLD>                                 2,775
<TRADING-ASSETS>                                 2,847
<INVESTMENTS-HELD-FOR-SALE>                  2,138,796
<INVESTMENTS-CARRYING>                       2,341,661
<INVESTMENTS-MARKET>                         2,354,150
<LOANS>                                     12,107,273
<ALLOWANCE>                                    179,126
<TOTAL-ASSETS>                              18,058,198
<DEPOSITS>                                  12,612,633
<SHORT-TERM>                                 2,218,875
<LIABILITIES-OTHER>                            403,218
<LONG-TERM>                                  1,460,003
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                        90,021
<OTHER-SE>                                   1,273,448
<TOTAL-LIABILITIES-AND-EQUITY>              18,058,198
<INTEREST-LOAN>                                784,128
<INTEREST-INVEST>                              243,166
<INTEREST-OTHER>                                 2,278
<INTEREST-TOTAL>                             1,029,572
<INTEREST-DEPOSIT>                             359,760
<INTEREST-EXPENSE>                             523,317
<INTEREST-INCOME-NET>                          506,255
<LOAN-LOSSES>                                   51,619
<SECURITIES-GAINS>                               6,136
<EXPENSE-OTHER>                                391,091
<INCOME-PRETAX>                                258,600
<INCOME-PRE-EXTRAORDINARY>                     258,600
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                   167,275
<EPS-PRIMARY>                                     2.03
<EPS-DILUTED>                                     2.01<F1>
<YIELD-ACTUAL>                                    4.10
<LOANS-NON>                                     67,384
<LOANS-PAST>                                    33,466
<LOANS-TROUBLED>                                     0
<LOANS-PROBLEM>                                      0
<ALLOWANCE-OPEN>                               179,049
<CHARGE-OFFS>                                   71,121
<RECOVERIES>                                    19,579
<ALLOWANCE-CLOSE>                              179,126
<ALLOWANCE-DOMESTIC>                                 0<F2>
<ALLOWANCE-FOREIGN>                                  0<F2>
<ALLOWANCE-UNALLOCATED>                              0<F2>
<FN>
<F1>Restated for Statement of Financial Accounting Standards No. 128, Earnings 
Per Share.
<F2>Available at year end only.
</FN>
        

</TABLE>