FIRST AMENDMENT TO
CREDIT AGREEMENT

| | FIRST
AMENDMENT TO CREDIT AGREEMENT (this First Amendment), dated as of
August 3, 2005, among WYETH, a Delaware corporation (the Company),
various lenders from time to time party to the Credit Agreement referred to below (the
Lenders), and JPMORGAN CHASE BANK, N.A. (f/k/a JPMORGAN CHASE BANK), as
Administrative Agent (in such capacity, the Administrative Agent).
Unless otherwise indicated, all capitalized terms used herein and not otherwise defined
shall have the respective meanings provided such terms in the Credit Agreement referred to
below.
| | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

W I T N E S S E T H :

| | WHEREAS,
the Company, the Lenders, J.P. Morgan Securities Inc. and Citigroup Global Markets Inc.,
as Co-Lead Arrangers and Joint Book Managers, Citibank North America, Inc., as Syndication
Agent, The Bank of Nova Scotia, Commerzbank AG, New York and Grand Cayman Branches, and
UBS AG, Cayman Islands Branch, as Co-Documentation Agents, and the Administrative Agent
are parties to a Credit Agreement, dated as of February 11, 2004 (the Credit
Agreement); and
| | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | WHEREAS,
subject to the terms and conditions of this First Amendment, the parties hereto wish to
amend the Credit Agreement as herein provided;
| | -----------------------------------------------------------------------------------------------------------------------------------------------

| | NOW,
THEREFORE, it is agreed:
| | -----------------------------

| | I.    
          Amendments to Credit Agreement.
| | ------------------------------------------------

| | 1.    
          Subsection 1.1 of the Credit Agreement is hereby amended by deleting the text
          3-Year Credit Agreement appearing in the definitions of
          Aggregate Facilities Commitments and Significant
          Usage Period in said subsection and inserting the text New
          5-Year Credit Agreement in lieu thereof.
| | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | 2.    
          The definition of Applicable Margin appearing in subsection
          1.1 of the Credit Agreement is hereby amended by (i) deleting the text
          .250% appearing in the proviso within such definition and inserting
          the text 0.100% in lieu thereof and (ii) deleting the table
          appearing in said definition and inserting the following table in lieu thereof:
| | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

> Rating
>  Period
>      
> Eurodollar
>  Rate Margin-----------------------------------------
>      
>      -------------------------Category A Period
>      
>      0.130%Category B Period
>      
>      0.175%Category C Period
>      
>      0.265%Category D Period
>      
>      0.300%Category E Period
>      
>      0.425%Category F Period
>      
>      0.600%.

| | 3.    
          The definition of Significant Usage Period appearing in
          subsection 1.1 of the Credit Agreement is hereby amended by deleting the text
          25% appearing in the proviso within such definition and inserting
          the text 50% in lieu thereof.
| | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | 4.    
          Subsection 1.1 of the Credit Agreement is hereby further amended by deleting the
          definitions of Category A Period, Category B
          Period, Category C Period, Category D
          Period, Category E Period, Category F
          Period and Facility Fee Percentage appearing in
          said subsection in their entirety and inserting the following new definitions in
          lieu thereof:
| | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | Act:
as defined in subsection 8.17.
| | -------------------------------------

| | Category
A Period: subject to the Category Rules, at any time that either (i) the S&P
Credit Rating is A+ or better and the Short-Term Ratings are Tier I or (ii) the
Moodys Credit Rating is A1 or better and the Short-Term Ratings are Tier I.
| | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | Category
B Period: subject to the Category Rules, at any time that either (i) the S&P
Credit Rating is A or better or (ii) the Moodys Credit Rating is A2 or better and in
either case a Category A Period is not then in effect.
| | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | Category
C Period: subject to the Category Rules, at any time that either (i) the S&P
Credit Rating is A- or (ii) the Moodys Credit Rating is A3.
| | ----------------------------------------------------------------------------------------------------------------------------------------------------

| | Category
D Period: subject to the Category Rules, at any time that either (i) the S&P
Credit Rating is BBB+ or (ii) the Moodys Credit Rating is Baa1.
| | --------------------------------------------------------------------------------------------------------------------------------------------------------

| | Category
E Period: subject to the Category Rules, at any time that either (i) the S&P
Credit Rating is BBB or (ii) the Moodys Credit Rating is Baa2.
| | -------------------------------------------------------------------------------------------------------------------------------------------------------

| | Category
F Period: subject to the Category Rules, at any time either (i) the S&P
Credit Rating is BBB- or lower or (ii) the Moodys Credit Rating is Baa3 or lower.
| | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | Facility
Fee Percentage: a percentage equal to at any time (i) during a Category A
Period, 0.070%, (ii) during a Category B Period, 0.075%, (iii) during a Category C Period,
0.085%, (iv) during a Category D Period, 0.100%, (v) during a Category E Period, 0.125%
and (vi) during a Category F Period, 0.150%.
| | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | New
5-Year Credit Agreement: the Credit Agreement, dated as of August 3, 2005,
among the Company, the lenders party thereto, JPMCB, as administrative agent, and Citicorp
USA Inc., as syndication agent, as in effect from time to time.
| | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | 5.    
          Subsection 2.18 of the Credit Agreement is hereby amended by deleting each
          reference to 3-Year Credit Agreement appearing therein and inserting
          the text New 5-Year Credit Agreement in lieu thereof.
| | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | 6.    
          Subsection 3.11 of the Credit Agreement is hereby amended by deleting such
          subsection in its entirety and inserting the following new subsection 3.11 in
          lieu thereof:
| | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | 3.11
Purpose of Loans. This Agreement, and/or the proceeds of the Loans, will be used
(i) for the Companys general corporate and working capital purposes and (ii) to
support commercial paper, if any.
| | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | 7.    
          Subsection 5.2 of the Credit Agreement is hereby amended by deleting the
          introductory clause therein and inserting the following new introductory clause
          in lieu thereof:
| | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | Furnish
to the Administrative Agent; provided that, with respect to any report, financial
statement or other information required to be delivered pursuant to Subsection 5.2(c)
which has been posted on the Companys website on the Internet at the website address
at www.wyeth.com, at sec.gov/edaux/searches.htm or at another website identified in
a notice delivered to the Administrative Agent and accessible by the Administrative Agent
without charge shall be deemed to have been furnished by the Company (it being agreed that
upon the request of the Administrative Agent, the Company shall deliver paper copies of
any such report, financial statement or other information to the Administrative
Agent):
| | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | 8.    
          Subsection 6(f) of the Credit Agreement is hereby amended by deleting the text
          30 days appearing therein and inserting the text 60 days
          in lieu thereof.
| | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | 9.    
          Section  8 of the Credit Agreement is hereby amended by inserting the
          following new Section 8.17:
| | ----------------------------------------------------------------------------------------------------------------------------

| | Section
8.17 Patriot Act. Each Lender subject to the USA PATRIOT ACT (Title 111 of Pub. L.
107-56 (signed into law October 26, 2001)) (the Act) hereby notifies
the Company that pursuant to the requirements of the Act, it is required to obtain, verify
and record information that identifies the Company and other information that will allow
such Lender to identify the Company in accordance with the Act.
| | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | 10.    
          Subsection 7.1 of the Credit Agreement is hereby amended by deleting the last
          sentence thereof in its entirety and inserting the following new sentence in
          lieu thereof:
| | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | None of
the Syndication Agent, the Co-Documentation Agent or the Co-Lead Arrangers shall have any
duties under this Agreement or assume (or be deemed to have assumed) any obligation or
relationship of agency or trust with or for the Company or any of its Subsidiaries.
| | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | 11.    
          Subsection 7.9 of the Credit Agreement is hereby amended by inserting the
          parenthetical (so long as no Default or Event of Default then exists under
          subsection 6(a) or (e)) immediately after the text which
          successor appearing in the second sentence thereof.
| | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | 12.    
          Subsection 8.5 of the Credit Agreement is hereby amended by deleting clause (d)
          thereof in its entirety and inserting the following new clause (d) in lieu
          thereof:
| | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | (d)
to pay, indemnify, and hold each Lender, the Administrative Agent, each of their
               respective affiliates, and each officer, director, employee, agent and other
               representative of the foregoing Persons (each, an indemnified
               party) harmless from and against, any and all other liabilities,
               obligations, losses, damages, penalties, actions, judgments, suits, costs,
               expenses or disbursements of any kind or nature whatsoever with respect to the
               execution, delivery, enforcement, performance and administration of this
               Agreement and any such other documents and the use, or proposed use, of proceeds
               of the Loans (all the foregoing, collectively, the indemnified
               liabilities).
| | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | 13.    
          Subsection 8.14 of the Credit Agreement is hereby amended by (i) deleting the
          text which is a prospective or actual Transferee appearing in the
          parenthetical of the introductory clause thereof and (ii) inserting the text
          (or any of its affiliates) following the text Lender in
          clause (b) thereof.
| | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | II.    
          Miscellaneous Provisions
| | ------------------------------------------

| | 1.    
          In order to induce the Lenders to enter into this First Amendment, the Company
          hereby represents and warrants that (i) no Default or Event of Default exists as
          of the Amendment Effective Date, both before and after giving effect to this
          First Amendment and (ii) all of the representations and warranties contained in
          the Credit Agreement are true and correct in all material respects on the
          Amendment Effective Date, both before and after giving effect to this First
          Amendment, with the same effect as though such representations and warranties
          had been made on and as of the Amendment Effective Date (it being understood
          that any representation or warranty made as of a specific date shall be true and
          correct in all material respects as of such specific date).
| | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | 2.    
          This First Amendment is limited as specified and shall not constitute a
          modification, acceptance or waiver of any other provision of the Credit
          Agreement.
| | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | 3.    
          This First Amendment may be executed in any number of counterparts and by the
          different parties hereto on separate counterparts, each of which counterparts
          when executed and delivered shall be an original, but all of which shall
          together constitute one and the same instrument. A complete set of counterparts
          shall be lodged with the Company and the Administrative Agent.
| | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | 4.    
          THIS FIRST AMENDMENT AND THE RIGHTS AND OBLIGATIONS OF THE PARTIES HEREUNDER
          SHALL BE CONSTRUED IN ACCORDANCE WITH AND GOVERNED BY THE LAW OF THE STATE OF
          NEW YORK.
| | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | 5.    
          This First Amendment shall become effective on the date (the Amendment
          Effective Date) when (i) the Company and each of the Lenders shall
          have signed a counterpart hereof (whether the same or different counterparts)
          and shall have delivered (including by way of facsimile transmission) the same
          to White & Case LLP, 1155 Avenue of the Americas, New York, NY 10036
          Attention: May Yip (facsimile number 212-354-8113) and (ii) the New 5-Year
          Credit Agreement shall have become effective in accordance with its terms.
| | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | 6.    
          From and after the Amendment Effective Date, all references in the Credit
          Agreement shall be deemed to be references to the Credit Agreement as modified
          hereby.
| | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

_________________

---

| | IN
WITNESS WHEREOF, the parties hereto have caused their duly authorized officers to execute
and deliver this Amendment as of the date first above written.
| | -----------------------------------------------------------------------------------------------------------------------------------------------------------

|
|
|
|

---

|
|
|
|

---

|
|
|
|

---

|
|
|
|

---

|
|
|
|
|

---

|
|
|
|
|

---

|
|
|
|
|

---

|
|
|
|
|

---

|
|
|
|

---

|
|
|
|

---

|
|
|
|

---

|
|
|
|
|

---

|
|
|
|

---

|
|
|
|

---

|
|
|
|

---