EXHIBIT 15

Accountants' Acknowledgment

To the Board of Directors and the Shareholders of Pfizer Inc.:

We hereby acknowledge our awareness of the use therein of our report dated May 11, 2017, included within the Quarterly Report on Form 10-Q of Pfizer Inc. for the quarter ended April 2, 2017 in the following Registration Statements:

-Form S-8 dated October 27, 1983 (File No. 2-87473),

-Form S-8 dated March 22, 1990 (File No. 33-34139),

-Form S-8 dated January 24, 1991 (File No. 33-38708),

-Form S-8 dated November 18, 1991 (File No. 33-44053),

-Form S-8 dated May 27, 1993 (File No. 33-49631),

-Form S-8 dated May 19, 1994 (File No. 33-53713),

-Form S-8 dated October 5, 1994 (File No. 33-55771),

-Form S-8 dated December 20, 1994 (File No. 33-56979),

-Form S-8 dated March 29, 1996 (File No. 333-02061),

-Form S-8 dated September 25, 1997 (File No. 333-36371),

-Form S-8 dated June 19, 2000 (File No. 333-39610),

-Form S-8 dated June 19, 2000 (File No. 333-39606),

-Form S-8 dated April 27, 2001 (File No. 333-59660),

-Form S-8 dated April 16, 2003 (File No. 333-104581),

-Form S-8 dated April 16, 2003 (File No. 333-104582),

-Form S-8 dated November 18, 2003 (File No. 333-110571),

-Form S-8 dated December 18, 2003 (File No. 333-111333),

-Form S-8 dated April 26, 2004 (File No. 333-114852),

-Form S-8 dated March 1, 2007 (File No. 333-140987),

-Form S-4 dated March 27, 2009 (File No. 333-158237),

-Form S-8 dated October 16, 2009 (File No. 333-162519),

-Form S-8 dated October 16, 2009 (File No. 333-162520),

-Form S-8 dated October 16, 2009 (File No. 333-162521),

-Form S-8 dated March 1, 2010 (File No. 333-165121),

-Form S-3ASR dated March 2, 2015 (File No. 333-202430),

-Form S-8 dated March 2, 2015 (File No. 333-202437), and

-Form S-4 dated September 3, 2015 (File No. 333-206758).

Pursuant to Rule 436 under the Securities Act of 1933 (the Act), such report is not considered a part of a registration statement prepared or certified by an independent registered public accounting firm, or a report prepared or certified by an independent registered public accounting firm within the meaning of Sections 7 and 11 of the Act.

/s/ KPMG LLP

New York, New York

May 11, 2017