Amendment Number 1 to Rights Agreement

         Pursuant to Section 27 of the Rights Agreement (the "Rights
Agreement"), dated as of November 11, 1999, by and between Abbott
Laboratories, an Illinois corporation (the "Company") and BankBoston, N.A.,
a national banking association (the "Rights Agent"), the Company and the
Rights Agent hereby agree that the Rights Agreement shall be amended as
follows:

         1. Section 3(b) shall be amended and restated to read in its
entirety as follows:

                  "(b) With respect to certificates for Common Shares
         outstanding as of the Record Date, until the Distribution Date,
         the Rights will be evidenced by such certificates registered in
         the names of the holders thereof, together with the Summary of
         Shareholder Rights Plan attached hereto as Exhibit C (the "Summary
         of Shareholder Rights Plan") and registered holders of Common
         Shares shall also be the registered holders of the associated
         Rights. Until the Distribution Date (or the earlier of the
         Redemption Date or the Final Expiration Date), the transfer of any
         certificate for Common Shares outstanding on the Record Date, with
         or without a copy of the Summary of Shareholder Rights Plan, shall
         also constitute the transfer of the Rights associated with the
         Common Shares represented thereby."

         2. Other than as set forth herein, all other provisions of the
Rights Agreement shall remain in full force and effect.

         IN WITNESS WHEREOF, the parties hereto have caused this Amendment
Number 1 to the Rights Agreement to be executed as of this 7th day of
December, 1999.


                                   ABBOTT LABORATORIES


                                   By:   /s/Jose M. de Lasa
                                         ------------------------
                                   Name: Jose M. de Lasa
                                   Its:  Senior Vice President, Secretary and
                                             General Counsel

                                   BANKBOSTON, N.A., as Rights Agent

                                   By:   /s/Ken Theva
                                         -------------------------
                                   Name: Ken Theva
                                   Its:  Director, Client Services




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