MONTREAL, QUEBEC--(Marketwire - Sept. 1, 2009) - 10:14 ET

THIS NEWS RELEASE IS INTENDED FOR DISTRIBUTION IN CANADA ONLY AND IS NOT AUTHORIZED FOR DISTRIBUTION TO UNITED STATES NEWSWIRE SERVICES OR FOR DISSEMINATION IN THE UNITED STATES.

Osisko Mining Corporation ("Osisko" or the "Corporation") (TSX:OSK)(FRANKFURT:EWX) is pleased to announce that it has closed its previously announced public offering, on a bought-deal basis, with a syndicate of underwriters (the "Underwriters"), led by Thomas Weisel Partners Canada Inc. and BMO Nesbitt Burns Inc., and including Dundee Securities Corporation. Osisko issued a total of 21,361,250 common shares at a price of C$7.00 per common share, for aggregate gross proceeds of C$149,528,750.

Osisko will use the proceeds of the offering for the development and construction of its Canadian Malartic Project and for working capital purposes.

The securities offered have not been registered under the U.S. Securities Act of 1933, as amended, and may not be offered or sold within the United States or to, or for the account or benefit of, U.S. persons absent registration or an applicable exemption from the registration requirements. This release shall not constitute an offer to sell or the solicitation of an offer to buy securities in the United States nor shall there be any sale of the securities in any State in which such offer, solicitation or sale would be unlawful.