MONTREAL, QUÉBEC--(Marketwire - Feb. 23, 2012) - Osisko Mining Corporation (the "Company" or "Osisko") (News - Market indicators)(FRANKFURT:EWX) is pleased to report that it has generated a net profit of $37.8 million ($0.10 per share) during the fourth quarter of 2011, and in its first partial year of operations has generated a net profit of $18.0 million ($0.05 per share) versus a loss of $17.8 million in 2010 ($0.05 per share).

Mine operating profits during the fourth quarter totaled $39.5 million, and $79.5 million for 2011. The Canadian Malartic mine reached commercial production on May 19, 2011.

Sean Roosen, President and Chief Executive Officer of Osisko, commenting on the results: "We are extremely pleased with the solid and profitable financial performance in our first year of start-up operations. The financial results clearly demonstrate the strength of the Canadian Malartic mine, which even in this first partial year of ramp-up operations has allowed us to capture great margins in this favorable gold price environment. We anticipate 2012 to provide a strong operating year for the Company as we complete the ramp-up and optimize operations at Canadian Malartic."

Highlights for the fourth quarter and the year were:

• Gold production of 79,718 ounces in the fourth quarter and 200,137 ounces for the year;
• Operating cash flow of $39.7 million in the fourth quarter and $85.7 million for 2011;
• Capital outlays of $356.8 million;
• Year-end increase in Canadian Malartic gold reserves by 200,000 oz. to 10.72 M oz., effectively replacing 2011 production.

The construction of Canadian Malartic was completed in late February 2011. Following a cold testing period of the processing plant, ore was introduced in the mill in early April and first gold was poured on April 13, 2011, approximately six years after the initial drill hole. Commercial production was achieved on May 19, 2011, representing the first day where the processing plant throughput averaged at least 60% of the 55,000 tonnes per day capacity. Sean Roosen noted: "The dedication and contribution of our employees was remarkable as we moved Canadian Malartic from an exploration project to one of Canada's largest gold mines in just over six years."

Following the positive contribution of the Canadian Malartic mine, in the fourth quarter the Company has recognized a tax benefit from prior year's losses which contributed $10.0 million to the net earnings.

In the fourth quarter of 2010, the Company had net earnings of $3.1 million, mainly as a result of unrealized gain on investments for $2.9 million, and a gain on premium of flow-through shares of $3.7 million, In 2010, finance costs were capitalized to property, plant and equipment as Osisko was developing its Canadian Malartic mine.

The Company has also strengthened its senior management team with the recent appointment of Ms. Hélène Cartier as Vice President, Environment and Sustainable Development following the departure of Jean-Sébastien David.

Key operating results

(in thousands of Canadian dollars, unless otherwise noted)

Steady progress at Canadian Malartic

Ramp up at Canadian Malartic continued throughout the period. Mill availability and performance were lower in October and November, but an improved performance was noted in December and continued into 2012. The mine production has continued to increase with greater flexibility as the pit is being developed. The grade processed has increased as the mine is gaining closer access to the higher grade ore areas. The operating team is also steadily gaining experience in mining near the old underground mining areas.

Production statistics are as follows:

As previously announced, the Company is building a new secondary crushing circuit designed to increase production to design capacity of 55,000-60,000 tonnes per day. The construction program is progressing well and is on target to deliver the first unit near the end of March and the complete program by the end of June.

The mine operating statement for the production period is as follows:

(in thousands of Canadian dollars, unless otherwise noted)

During the year, the Company exercised its option to purchase half of the Royal Gold royalty (previously owned by Barrick Gold) for US$1.5 million and re-purchased a 1% royalty interest from Géoconseils Jack Stoch Limitée in consideration for the issuance of 460,000 common shares of Osisko. This royalty was encumbering a portion of the Canadian Malartic and Barnat deposits and is part of a 2.5% Gross Metal Royalty interest that was granted as a result of the acquisition of certain claims of the Canadian Malartic property in March 2006. Following this purchase, only 60% of the recoverable gold ounces at the entire Canadian Malartic mine are subject to a 1.5% Net Smelter or Gross Metal Royalty, based on the most recently published reserve estimates.

Update on Resources and Reserves

The following resource and reserve estimates are dated as of January 1, 2012. Resources are based on a lower cut-off of approximately 0.30 g/t Au (0.286 to 0.312 g/t Au) and reserves/pit shell resources are based on a US $1200 gold price.

Consolidated global (in situ) resources for all Malartic area deposits (Canadian Malartic, South Barnat, Gouldie, Charlie, Jeffrey and Western Porphyry) are 372.95 Mt @ 1.02 g/t Au for 12.23 M oz gold in the Measured and Indicated category and 50.35 Mt @ 0.71 g/t Au for 1.16 M oz gold in the Inferred Category. This number excludes 2011 production and stockpiled inventory (approx. 230,000 oz. Au). Global (in situ) Inferred resources for the Hammond Reef deposit are estimated at 530.6 Mt @ 0.62 g/t Au for 10.52 M oz gold. Consolidated diluted in-pit resources for all Malartic area deposits (except Western Porphyry) are 345.49 Mt @ 0.99 g/t Au for 11.00 M oz gold in the Measured and Indicated category and 10.74 Mt @ 0.69 g/t Au for 0.24 M oz gold in the Inferred Category. These numbers also exclude 2011 production and stockpiled inventory (approx. 230,000 oz. Au). Diluted in-pit resources at Hammond Reef in the Inferred category are 336.6 Mt @ 0.63 g/t Au for 6.86 M oz gold.

The Proven & Probable reserve estimate at Malartic (main pit and three satellite pits excluding Western Porphyry) is 337.67 Mt @ 0.99 g/t Au for 10.72 M oz gold. This number excludes 2011 production (approx. 200,000 oz. Au).

Summary table of Resources and Reserves as of January 1, 2012

The Company continues to conduct exploration work on a regional basis around the Canadian Malartic infrastructure for additional resources and reserves.

Exploration and Development

A new resource estimate for Hammond Reef was released on November 7, 2011. New drilling by Osisko and Brett Resources from January 2010 to July 2011 (approximately 300,000 meters) has significantly increased the size of the deposit. Global inferred resource now stands at 10.52 million ounces of gold (based on 0.30 g/t Au lower cut-off), and in-pit inferred resource reached 6.86 million ounces at a diluted grade of 0.63 grams per tonne gold, based on a Whittle-optimized pit shell using a gold price of US$1,200 per ounce, a corresponding lower cut-off grade of 0.28 grams per tonne gold and a waste/ore strip ratio of 1.25.

Additional drilling continues since July 2011 to allow for the upgrade of the entire in-pit deposit to indicated category by the end of the first quarter of 2012 and measured and indicated category by the end of the second quarter 2012.

During the year, the Company has terminated its activities on various exploration projects, including Duparquet and Goldboro, which resulted in a charge of $16.0 million.

The Company continues to pursue growth opportunities by the evaluation of various projects and entering into exploration agreements.

Summary from the Company's financial position and results are as follows:

(in millions of Canadian dollars)

In August 2011 an amended and restated master funding and lease agreement has been signed with Caterpillar Financial Services for US$56.3 million to finance additional mining equipment for Canadian Malartic. As at December 31, 2011, US$45.6 million have been drawn on the increased facility.

In 2011, the Company made debt repayments of $11.8 million and completed two private placements of flow-through shares for $32.4 million.

Capital investments amounted to $59.5 million for the fourth quarter and $356.8 million for 2011 mainly for the Canadian Malartic construction, the Canadian Malartic expansion project and investments in exploration projects.

Outlook for 2012

With the introduction of a new pre-crushing plant which is expected to be fully completed by the end of June 2012, the Company expects to produce between 610,000 and 670,000 ounces at a cash cost ranging from $510/oz to $575/oz. The cash cost is expected to decrease substantially as the plant reaches full capacity, an increase of 65% compared to 2011. The non-cash charges are expected to be approximately $136 per ounce.

Capital expenditures are estimated at $219.2 million and are summarized below:

The Company expects to repay $86.9 million on its various credit facilities.

Non-IFRS Financial Performance Measures

The Company has included certain non-IFRS measures including "cash cost per ounce" and "cash margin per ounce" to supplement its financial statements, which are presented in accordance with International Financial Reporting Standards ("IFRS"). Refer to the Company's 2011 Management Discussion and Analysis.

Year-End 2011 Results Conference Call

Osisko will host a conference call on Friday, February 24, 2012 at 11:00 AM EST, where senior management will discuss the financial results and provide an update of the Company's activities. Those interested in participating in the conference call should dial in at 416-981-9000 (Toronto local and international), or 1-800-931-6421 (North American toll free). An operator will direct participants to the call. The call will be retransmitted for 14 days with the following dial in number: 416-626-4100 or Toll-free 1-800-558-5253, access code 21574696.

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. Luc Lessard, Eng., Senior Vice-President and Chief Operating Officer 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.

Cautionary Notes Concerning Estimates of Mineral Resources

This news release uses the terms measured, indicated and inferred resources as a relative measure of the level of confidence in the resource estimate. Readers are cautioned that mineral resources are not economic mineral reserves and that the economic viability of resources that are not mineral reserves has not been demonstrated. In addition, inferred resources are considered too geologically speculative to have any economic considerations applied to them. It cannot be assumed that all or any part of an inferred mineral resource will ever be upgraded to a higher category. Under Canadian rules, estimates of inferred mineral resources may not form the basis of feasibility or pre-feasibility studies or economic studies except for Preliminary Assessment as defined under NI 43-101. Readers are cautioned not to assume that that further work will lead to mineral reserves that can be mined economically.

Note Regarding Certain Measures of Performance

This press release contains certain non-IFRS measures, including "cash cost per ounce" and "cash margin per ounce". The Company believes that these measures, together with measures determined in accordance with IFRS, provides investors with an improved ability to evaluate the underlying performance of the Company. Non-IFRS measures do not have any standardized meaning prescribed under IFRS, and therefore they may not be comparable to similar measures employed by other companies. The data is intended to provide additional information and should not be considered in isolation or as a substitute for measures of performance prepared in accordance with IFRS.

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, further development of its Hammond Reef project and increasing of throughput at the mill to achieve design capacity at its Canadian Malartic mine, timely installation of the pre-crush circuit, increasing of mining fleet availability, increasing of production. 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 development of its Hammond Reef project and that the diligent ongoing optimizing of its operations at the Canadian Malartic mine including the installation of the secondary crushing circuit will be achieved and will, accordingly, improve its operating performance, 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, access to skilled consultants, mining development personnel, results of exploration and development activities, Osisko's limited experience with production and development stage mining operations, uninsured risks, regulatory changes, defects in title, availability of personnel, materials and equipment, timeliness of government approvals, actual performance of facilities, equipment and processes relative to specifications and expectations, unanticipated environmental impacts on operations market prices, 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.