**Exhibit 31.1**

**Certification of Chairman andChief Executive Officer**

**Pursuant to Section 302 of theSarbanes-Oxley Act of 2002**

 

I, Allen Chao, Chairman and Chief Executive Officer, certify that:

 

1. I have reviewed this quarterly report on Form 10-Q of WatsonPharmaceuticals, Inc.;

 

2. Based on my knowledge, this report does not contain any untruestatement of a material fact or omit to state a material fact necessary to makethe statements made, in light of the circumstances under which such statementswere made, not misleading with respect to the period covered by this report;

 

3. Based on my knowledge, the financial statements, and other financialinformation included in this report, fairly present in all material respectsthe financial condition, results of operations and cash flows of the registrantas of, and for, the periods presented in this report;

 

4. The registrant’s other certifying officer and I are responsible forestablishing and maintaining disclosure controls and procedures (as defined inExchange Act Rules 13a-15(e) and 15d-15(e)) for the registrant and have:

 

a) designed such disclosure controls and procedures,or caused such disclosure controls and procedures to be designed under oursupervision,  to ensure that materialinformation relating to the registrant, including its consolidatedsubsidiaries, is made known to us by others within those entities, particularlyduring the period in which this report is being prepared;

 

b) evaluated the effectiveness of the registrant’sdisclosure controls and procedures and presented in this report our conclusionsabout the effectiveness of the disclosure controls and procedures, as of theend of the period covered by this report based on such evaluation; and

 

c) disclosed in this report any change in the registrant’sinternal control over financial reporting that occurred during the registrant’smost recent fiscal quarter (the registrant’s fourth fiscal quarter in the caseof an annual report) that has materially affected, or is reasonably likely tomaterially affect, the registrant’s internal control over financial reporting;and

 

5. The registrant’s other certifying officer and I have disclosed,based on our most recent evaluation of internal control over financialreporting, to the registrant’s auditors and the audit committee of theregistrant’s board of directors (or persons performing the equivalentfunction):

 

a) all significant deficiencies and materialweaknesses in the design or operation of internal control over financialreporting which are reasonably likely to adversely affect the registrant’sability to record, process, summarize and report financial information; and

 

b) any fraud, whether or notmaterial, that involves management or other employees who have a significantrole in the registrant’s internal control over financial reporting.

 
| Date:  August 6,  2004 | ** ** |
|-----------------------------|------------|
|                        | By:        | **/s/  Allen Chao** |
|                        |       | Allen Chao, Ph.D. |
|                        | ** ** | Chairman and Chief  Executive Officer |
|                        | ** ** | (Principal Executive  Officer) |

 

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