Exhibit 11

WESTAMERICA BANCORPORATION

Computation of Earnings Per Share on Common and
Common Equivalent Shares and on Common Shares
Assuming Full Dilution

(In thousands, except per share data)	2004		2003		2002
Weighted average number of common shares outstanding — basic		31,821		32,849		33,686
Add exercise of options reduced by the number of shares that could have been purchased with the proceeds of such exercise		640		520		539
Weighted average number of common shares outstanding — diluted		32,461		33,269		34,225
Net income	$	95,218	$	95,063	$	87,138
Basic earnings per share	$	2.99	$	2.89	$	2.59
Diluted earnings per share		2.93		2.85		2.55