Osisko Mining Corporation Adopts Advance Notice By-Law

MONTREAL, QUEBEC--(Marketwire - Dec. 21, 2012) - Osisko Mining Corporation ("Corporation" or "Osisko") (TSX:OSK)(FRANKFURT:EWX) announces the approval and adoption by its board of directors (the "Board") of amendments to its by-laws ("By-Laws") to include advance notice provisions, the purpose of which is to require advance notice be provided to the Corporation in circumstances where nominations of persons for election to the Board are made by shareholders of the Corporation other than pursuant to: (i) a requisition of a meeting of shareholders made pursuant to the provisions of the Canada Business Corporations Act (the "Act"); or (ii) a shareholder proposal made pursuant to the provisions of the Act.

The purpose of the By-Law is to provide shareholders, directors and management of the Corporation with a clear framework for nominating directors. Among other things, the By-Law fixes a deadline by which holders of common shares of the Corporation must submit director nominations to the Corporation prior to any annual or special meeting of shareholders and sets forth the minimum information that a shareholder must include in the notice to the Corporation for the notice to be in proper written form.

In the case of an annual meeting of shareholders, notice to the Corporation must be made not less than 30 nor more than 65 days prior to the date of the annual meeting; provided, however, that in the event that the annual meeting is to be held on a date that is less than 50 days after the date on which the first public announcement of the date of the annual meeting was made, notice may be made not later than the close of business on the 10^th day following such public announcement.

In the case of a special meeting of shareholders (which is not also an annual meeting), notice to the Corporation must be made not later than the close of business on the 15^th day following the day on which the first public announcement of the date of the special meeting was made.

The By-Law is effective immediately and will be placed before shareholders for ratification at the next annual and special meeting of shareholders of the Corporation. A copy of the By-Law has been filed under the Corporation's profile at www.sedar.com.

About Osisko Mining Corporation

Osisko Mining Corporation operates the Canadian Malartic Gold Mine in Malartic, Quebec and is pursuing exploration on a number of properties, including the Hammond Reef Gold Project in Northern Ontario.