FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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(Print or Type Responses)

1. Name and Address of Reporting Person * HANSEN DENNIS R   2. Issuer Name and Ticker or Trading Symbol WESTAMERICA BANCORPORATION [WABC] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) Exec. Off. Primary Subsidiary (Last) (First) (Middle) 3. Date of Earliest Transaction (Month/Day/Year) 04/28/2006 (Street)   4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Filing(Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 04/28/2006   M   1,900 A $ 32.7917 1,900 D   Common Stock 04/28/2006   S   1,900 D $ 51.087 0 D   Common Stock 04/28/2006   M   100 A $ 32.7917 100 D   Common Stock 04/28/2006   S   100 D $ 51.09 0 D   Common Stock 04/28/2006   M   300 A $ 32.7917 300 D   Common Stock 04/28/2006   S   300 D $ 51.11 0 D   Common Stock 04/28/2006   M   684 A $ 32.7917 684 D   Common Stock 04/28/2006   S   684 D $ 51.12 0 D   Common Stock 04/28/2006   M   16 A $ 32.7917 16 D   Common Stock 04/28/2006   S   16 D $ 51.13 0 D   Common Stock               5,210 (1) I Deferred Common Stock               18,742.697 (2) I ESOP Common Stock               250 (4) I by Son

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Non-Qualified Stock Option (right to buy)

$ 32.7917

04/28/2006

M

1,900

01/21/1999(3)

01/21/2008

Common Stock

1,900

$ 0

11,300

D

Non-Qualified Stock Option (right to buy)

$ 32.7917

04/28/2006

M

100

01/21/1999(3)

01/21/2008

Common Stock

100

$ 0

11,200

D

Non-Qualified Stock Option (right to buy)

$ 32.7917

04/28/2006

M

300

01/21/1999(3)

01/21/2008

Common Stock

300

$ 0

10,900

D

Non-Qualified Stock Option (right to buy)

$ 32.7917

04/28/2006

M

684

01/21/1999(3)

01/21/2008

Common Stock

684

$ 0

10,216

D

Non-Qualified Stock Option (right to buy)

$ 32.7917

04/28/2006

M

16

01/21/1999(3)

01/21/2008

Common Stock

16

$ 0

10,200

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
HANSEN DENNIS R			Exec. Off. Primary Subsidiary

Signatures

by Shirley Kolin, Attorney-in-Fact For: Dennis R. Hansen		05/02/2006
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	Restricted Performance Shares that vested upon meeting performance criteria on 1/26/06 were previously reported as direct holding pending delivery in March to WAB Deferral Plan trust.
(2)	Includes allocations through 3/31/06 to Westamerica Bancorporation's Tax Deferred Savings/Retirement (ESOP) Plan.
(3)	Shares vest ratably over three years beginning one year from date of grant.
(4)	The reporting person disclaims beneficial ownership of all securities held by his son, and this report should not be deemed an admission that the reporting person is beneficial owner of such securities for purposes of Section 16 or for any other purpose.

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