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Exhibit 12(a)

Aon Corporation and Consolidated Subsidiaries
Combined With Unconsolidated Subsidiaries
Computation of Ratio of Earnings to Fixed Charges

			Six Months Ended June 30,				Years Ended December 31,
			2003		2002		2002		2001		2000		1999		1998
			(millions except ratios)
Income before provision for income taxes and minority interest			$	501	$	287	$	793	$	309	$	854	$	635	$	931
Add back fixed charges:
	Interest on indebtedness			55		59		124		127		140		105		87
	Interest credited on investment-type insurance contracts			2		21		29		56		71		77		72
	Interest on ESOP			—		—		—		—		—		1		2
	Portion of rents representative of interest factor			27		28		59		57		54		49		51
		Income as adjusted	$	585	$	395	$	1,005	$	549	$	1,119	$	867	$	1,143
Fixed charges:
	Interest on indebtedness		$	55	$	59	$	124	$	127	$	140	$	105	$	87
	Interest credited on investment-type insurance contracts			2		21		29		56		71		77		72
	Interest on ESOP			—		—		—		—		—		1		2
	Portion of rents representative of interest factor			27		28		59		57		54		49		51
		Total fixed charges	$	84	$	108	$	212	$	240	$	265	$	232	$	212
Ratio of earnings to fixed charges				7.0		3.7		4.7		2.3		4.2		3.7		5.4

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Exhibit 12(a)

Aon Corporation and Consolidated Subsidiaries Combined With Unconsolidated Subsidiaries Computation of Ratio of Earnings to Fixed Charges