<TABLE> <S> <C>
<PAGE>
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE ARTHUR
J. GALLAGHER & CO. CONSOLIDATED FINANCIAL STATEMENTS INCLUDED IN THE FORM 10-Q
FOR THE SIX-MONTH PERIOD ENDED JUNE 30, 2000 AND IS QUALIFIED IN ITS ENTIRETY BY
REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<RESTATED>
<MULTIPLIER> 1,000
<S> <C> <C>
<PERIOD-TYPE> 6-MOS 6-MOS
<FISCAL-YEAR-END> DEC-31-2000 DEC-31-1999
<PERIOD-START> JAN-01-2000 JAN-01-1999
<PERIOD-END> JUN-30-2000 JUN-30-1999
<CASH> 179,757 156,142
<SECURITIES> 64,949 60,341
<RECEIVABLES> 386,901 329,797
<ALLOWANCES> 892 951
<INVENTORY> 0 0
<CURRENT-ASSETS> 674,968 588,030
<PP&E> 122,050 108,771
<DEPRECIATION> 83,250 73,481
<TOTAL-ASSETS> 928,751 820,422
<CURRENT-LIABILITIES> 642,744 587,888
<BONDS> 0 0
0 0
0 0
<COMMON> 38,151 37,073
<OTHER-SE> 231,676 178,725
<TOTAL-LIABILITY-AND-EQUITY> 928,751 820,422
<SALES> 299,106 269,631
<TOTAL-REVENUES> 312,697 284,250
<CGS> 167,799 153,584
<TOTAL-COSTS> 167,799 153,584
<OTHER-EXPENSES> 97,545 89,364
<LOSS-PROVISION> 797 (180)
<INTEREST-EXPENSE> 274 685
<INCOME-PRETAX> 46,282 40,797
<INCOME-TAX> 16,199 13,954
<INCOME-CONTINUING> 30,083 26,843
<DISCONTINUED> 0 0
<EXTRAORDINARY> 0 0
<CHANGES> 0 0
<NET-INCOME> 30,083 26,843
<EPS-BASIC> .80 .73
<EPS-DILUTED> .75 .69
</TABLE>