Osisko Acquires Ground in Emerging Gold Belt in Mexico and Identifies Large Gold Anomaly

MONTREAL, QUEBEC -- (Marketwire) -- 10/09/12 -- Osisko Mining Corporation (the "Company" or "Osisko") (TSX: OSK)(FRANKFURT: EWX) is pleased to announce that it has acquired through staking approximately one million hectares of ground in an emerging gold rich mineral belt in Mexico.

A systematic greenfields exploration program was initiated in late 2011, starting with a high-density stream sediment survey comprising over 4,000 samples. Detailed mapping, geochemistry and geophysics were subsequently completed over identified anomalous areas. The work to date has identified a large magmatic-hydrothermal system with a coincident five square kilometre Au-Cu-Ag soil and lithogeochemical anomaly, all located within a 14 square kilometre hydrothermal alteration zone. This target is currently undergoing preparatory work for a preliminary 10,000 metre drill program. Two additional anomalies were also identified, and work is underway to bring them to drill-ready status.

Sean Roosen, President and Chief Executive Officer, commented: "We are excited by the preliminary results of our exploration efforts in Mexico. We believe that we can deliver significant value to our shareholders through systematic greenfields exploration programs, and continue to work towards building the team and the knowledge base to pursue significant new gold discoveries".

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.

Mr. Robert Wares, P. Geo. and Executive Vice-President of Osisko is the Qualified Person who has reviewed this news release and is responsible for the technical information reported herein, including verification of the data disclosed including the sampling, analytical and test data underlying the technical information.

Forward-Looking Statements

Certain statements contained in this press release may be deemed "forward-looking statements". All statements in this release, other than statements of historical fact, that address events or developments that Osisko expects to occur, are forward looking statements. Forward looking statements are statements that are not historical facts and are generally, but not always, identified by the words "expects", "plans", "anticipates", "believes", "intends", "estimates", "projects", "potential", "scheduled" and similar expressions, or that events or conditions "will", "would", "may", "could" or "should" occur including, without limitation, obtaining favourable results from our exploration activities in Mexico. Although Osisko believes the expectations expressed in such forward-looking statements are based on reasonable assumptions, including, without limitation, that all technical, economical and financial conditions will be met in order to warrant further exploration work in Mexico, such statements are not guarantees of future performance and actual results may differ materially from those in forward looking statements. Factors that could cause the actual results to differ materially from those in forward-looking statements include gold prices, results of exploration and development activities, uninsured risks, regulatory changes, defects in title, availability of personnel, materials and equipment, timeliness of government approvals, continued availability of capital and financing and general economic, market or business conditions. These factors are discussed in greater detail in Osisko's most recent Annual Information Form and in the most recent Management Discussion and Analysis filed on SEDAR, which also provide additional general assumptions in connection with these statements. Osisko cautions that the foregoing list of important factors is not exhaustive. Investors and others who base themselves on forward-looking statements should carefully consider the above factors as well as the uncertainties they represent and the risk they entail. Osisko believes that the expectations reflected in those forward-looking statements are reasonable, but no assurance can be given that these expectations will prove to be correct and such forward-looking statements included in this press release should not be unduly relied upon. These statements speak only as of the date of this press release.

Contacts:

John Burzynski

Vice-President Corporate Development

(416) 363-8653
www.osisko.com


Sylvie Prud'homme

Director of Investor Relations

(514) 735-7131

Toll Free: 1-888-674-7563