WHITEHOUSE STATION, N.J. March 12, 2004 – Merck & Co., Inc. has received a letter from the Canada Customs and Revenue Agency (CCRA) stating that the spin-off of Medco Health Solutions, Inc. by Merck & Co., Inc. on August 19, 2003, meets the requirements of paragraph 86.1(2)(e) of the Income Tax Act (Canada). Therefore, shareholders are entitled to elect to treat the distribution of Medco Health Solutions, Inc. shares as tax-free.

Please see the CCRA web site for additional information.

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