Exhibit 12

Marshall & Ilsley Corporation

Computation of Ratio of Earnings to Fixed Charges

($000’s)

	Years Ended December 31,
	2002			2001			2000			1999			1998
Earnings:
Earnings before income taxes and cumulative effect of changes in accounting principles	$	718,592		$	501,045		$	470,350		$	527,939		$	465,285
Fixed charges, excluding interest on deposits		301,518			321,059			321,812			222,172			206,546
Earnings including fixed charges but excluding interest on deposits		1,020,110			822,104			792,162			750,111			671,831
Interest on deposits		283,385			566,899			772,016			585,864			564,540
Earnings including fixed charges and interest on deposits	$	1,303,495		$	1,389,003		$	1,564,178		$	1,335,975		$	1,236,371
Fixed Charges:
Interest Expense:
Short-term borrowings	$	150,310		$	188,587		$	224,187		$	142,294		$	126,624
Long-term borrowings		127,343			110,842			78,773			63,145			66,810
One-third of rental expense for all operating leases (the amount deemed representative of the interest factor)		23,865			21,630			18,852			16,733			13,112
Fixed charges excluding interest on deposits		301,518			321,059			321,812			222,172			206,546
Interest on deposits		283,385			566,899			772,016			585,864			564,540
Fixed charges including interest on deposits	$	584,903		$	887,958		$	1,093,828		$	808,036		$	771,086
Ratio of Earnings to Fixed Charges:
Excluding interest on deposits		3.38	x		2.56	x		2.46	x		3.38	x		3.25	x
Including interest on deposits		2.23	x		1.56	x		1.43	x		1.65	x		1.60	x