MONTREAL, QUEBEC--(Marketwire - Oct. 3, 2012) - Osisko Mining Corporation (the "Company" or "Osisko") (TSX:OSK)(FRANKFURT:EWX) is proud to announce that it has deposited the amount of $12.7 million with the Quebec Government, to cover the cost of rehabilitating its new Canadian Malartic mine site in the Abitibi-Temiscamingue region of Quebec. Amounts deposited to date total $34.8 million. Osisko intends to deposit an additional $11.6 million next year, thereby completing its commitment to deposit in the first years of operations, the entire financial guarantee covering the total costs of the environmental rehabilitation of its Canadian Malartic mine.

Osisko is the first mining company in Quebec to deposit its full financial guarantee at commencement of operations. This full deposit exceeds the legislation currently in force in Quebec.

Sean Roosen, President and Chief Executive Officer, noted: "By accelerating the deposit of this significant financial guarantee, Osisko ensures that Quebec taxpayers will never be responsible for assuming the rehabilitation costs of the Canadian Malartic mine. We are proud of our leadership with the measure, and in our ability to demonstrate corporate responsibility towards the citizens of Quebec and our shareholders."

The Canadian Malartic mine commenced operations in May 2011. Canadian Malartic is an important contributor to Quebec's economy, particularly in the Abitibi-Temiscamingue region, where it employs directly more than 600 individuals.

About Osisko

Osisko Mining Corporation operates the Canadian Malartic gold mine in Malartic, Quebec and is pursuing exploration activities on various projects, including the Hammond Reef gold project in Northern Ontario.

Contact Information:

John Burzynski
Vice-President Corporate Development
Tel. (416) 363-8653

Sylvie Prud'homme
Director of Investor Relations
Tel. (514) 735-7131
Toll Free: 1-888-674-7563