Exhibit 31.1

# CERTIFICATION OF
DISCLOSUREAS ADOPTED PURSUANT TOSECTION 302 OF THE
SARBANES-OXLEY ACT OF 2002

I,
Robert Essner, certify that:

| | 1. | I have reviewed this Quarterly Report on Form 10-Q of Wyeth (the registrant);
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| | 2. | Based on my knowledge, this report does not contain any untrue statement of a
               material fact or omit to state a material fact necessary to make the statements
               made, in light of the circumstances under which such statements were made, not
               misleading with respect to the period covered by this report;
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| | 3. | Based on my knowledge, the financial statements, and other financial information
               included in this report, fairly present in all material respects the financial
               condition, results of operations and cash flows of the registrant as of, and
               for, the periods presented in this report;
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| | 4. | The registrants other certifying officers and I are responsible for
               establishing and maintaining disclosure controls and procedures (as defined in
               Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial
               reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the
               registrant and have:
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| | (a) | Designed
such disclosure controls and procedures, or caused such disclosure controls and
procedures to be designed under our supervision, to ensure that material information
relating to the registrant, including its consolidated subsidiaries, is made known to us
by others within those entities, particularly during the period in which this report is
being prepared;
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| | (b) | Designed such internal control over financial reporting, or caused such internal
                    control over financial reporting to be designed under our supervision, to
                    provide reasonable assurance regarding the reliability of financial reporting
                    and the preparation of financial statements for external purposes in accordance
                    with generally accepted accounting principles;
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| | (c) | Evaluated the effectiveness of the registrants disclosure controls and
                    procedures and presented in this report our conclusions about the effectiveness
                    of the disclosure controls and procedures, as of the end of the period covered
                    by this report based on such evaluation; and
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| | (d) | Disclosed in this report any change in the registrants internal control
                    over financial reporting that occurred during the registrants most recent
                    fiscal quarter (the registrants fourth fiscal quarter in the case of an
                    annual report) that has materially affected, or is reasonably likely to
                    materially affect, the registrants internal control over financial
                    reporting; and
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| | 5. | The registrants other certifying officers and I have disclosed, based on
               our most recent evaluation of internal control over financial reporting, to the
               registrants auditors and the audit committee of the registrants
               board of directors (or persons performing the equivalent functions):
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| | (a) | All
               significant deficiencies and material weaknesses in the design or operation of
               internal control over financial reporting
which are reasonably likely to adversely affect the registrants ability to record,
process, summarize and report financial information; and
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| | (b) | Any fraud, whether or not material, that involves management or other employees
                    who have a significant role in the registrants internal control over
                    financial reporting.
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|Dated: August 5,
2005 |  | By: /s/           
         Robert Essner
     
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    Robert Essner
       Chairman, President and Chief
Executive Officer
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