Exhibit 99.4

May 17, 2012

CONSENT OF HERBERT A. SMITH

United States Securities and Exchange Commission

Gentlemen:

In connection with Silver Wheaton Corp.’s registration statements on Form S−8 (File No. 333−128128) and Form F-10 (File No. 333-167567), filed under the United States Securities Act of 1933, as amended (the “Registration Statements”) I, Herbert A. Smith, P.Eng, Principal Mining Engineer and Mining Manager, AMC Mining Consultants (Canada) Limited, hereby consent to the inclusion and incorporation by reference in the Registration Statements of information derived from the technical report dated April 16, 2012 “San Dimas Property San Dimas District, Durango and Sinaola States, Mexico, Technical Report for Silver Wheaton Corp.”

Yours truly,

/s/ Herbert A. Smith                                        
Herbert A. Smith, P.Eng
Principal Mining Engineer and Mining Manager,
AMC Mining Consultants (Canada) Limited