Osisko Releases Second Quarter 2010 Results

MONTREAL, QUEBEC -- (Marketwire) -- 08/10/10 -- Osisko Mining Corporation (the 'Company' and 'Osisko') (TSX: OSK)(FRANKFURT: EWX) is pleased to report its second quarter financial results for the period ended June 30, 2010.

Highlights

--  Acquisition of 77% interest in Brett Resources Inc. and its Hammond
    Reef Project;

--  Continued progress on the construction and development of the Canadian
    Malartic Project with outlays of $116.4 million;

--  Near completion of relocation with the transfer of long-term care
    facility and acquisition of remaining homes;

--  Continued extensive exploration and definition drilling activities to
    grow the reserve and resource base;

--  Implementation of a Shareholder Rights Plan;

--  Net loss of $8.4 million for the period and $7.1 million year-to-date.

During the second quarter of 2010, the Company's incurred a loss of $8.4 million ($0.02 per share) compared to a loss of $5.8 million ($0.02 per share) in the corresponding period of 2009. The higher loss incurred is mainly due to higher costs from increased activities as the Company transitions to become a leading intermediate gold producer, and cost related to the implementation of a Shareholder Rights Plan. For the year-to-date, the loss amounted to $7.1 million ($0.02 per share) compared to $6.6 million ($0.03 per share) in the first semester of 2009. The increase is mainly due to additional costs associated with the growth in the Company's activities, and higher stock based compensation offset partially by higher interest income due to higher cash balances on hand.

Acquisition of Brett Resources

On May 19, 2010, the Company acquired 77% of Brett Resources Inc. ('Brett') following a friendly takeover offer announced on March 22, 2010. Under the terms of the offer, Osisko issued 0.34 shares of Osisko and $0.0001 in cash in return for each share of Brett. Osisko has filed a formal plan of arrangement with Brett on July 13, 2010 and will vote for the proposal in conjunction with the Special Brett Shareholders' Meeting to be held on August 11, 2010.

The acquisition of the Hammond Reef deposit enhances Osisko's reserve and resource base and provides the opportunity to see Osisko become a one million ounce per year gold producer by 2015-2016. Mr. Sean Roosen, President and CEO, noted 'We believe that the Hammond Reef deposit has the potential to have a production profile similar to our Canadian Malartic Project. We have significantly ramped up the definition and exploration drilling program at Hammond, and we feel very confident that we will see the overall size of the deposit grow as a result.'

The Hammond Reef gold project is located near Atikokan, Ontario. A Preliminary Assessment Study (the 'Study') was completed in November 2009 outlining an initial 14 year mine life operating at 50,000 tonnes per day. Over the first six years, on average, Hammond Reef is expected to produce 463,000 ounces of gold per year at cash costs of US$382 per ounce (including royalties, net of silver credits). Over the life of mine, Hammond Reef is expected to produce a total of 5.13 million ounces of gold at an average rate of 369,000 ounces per year and average cash costs of US$442 per ounce (including royalties, net of silver credits). Using a gold price of US$990 per ounce the Study shows that Hammond Reef has an after-tax net present value of US$811 million (using a 5% discount rate) and an internal rate of return of 22.9%. The study is available on SEDAR.

In addition to the current resource, Hammond Reef offers exciting exploration potential as recent drilling confirmed continuity of mineralization along strike two kilometers northeast of the existing resource. Brett has also identified several parallel structures in the project area that host mineralization similar to the main body.

Canadian Malartic Project

The Canadian Malartic Project is progressing well with the advancement rate reaching approximately 60% completion. Key milestones during the quarter included:

--  Finalizing the equipment/bulk material purchasing phase;

--  Expediting the delivery of process equipment to site;

--  Completion of concrete foundation and structural steel erection work
    at the processing plant;

--  Beginning of equipment installation at plant;

--  Delivery of Administration/Mine Service Building;

--  Near completion of 120kV electrical line and main sub-station work;

At quarter end, $619.1 million had been spent on the Project, with an additional $204.8 million committed.

A fast track construction program is being implemented that is forecasted to increase the project cost estimate by 3% to $956 million. The Project is now scheduled for completion in early May 2011.

Relocation

The relocation program is nearing completion with the acquisition of the remaining houses on the property. The Company also transferred the new long-term health care facility to the health authorities completing the institutional construction phase of the relocation program. The closure of the infrastructure is 98% completed.

Exploration Program

The Company continued to pursue its efforts to build on its current reserve/resource base. Some 174,300 meters were drilled in 2010, including 95,400 meters during the second quarter.

Shareholder Rights Plan

On May 17, 2010, the Company adopted a Shareholder Rights Plan ('Plan'). The Plan is designed to ensure that Osisko's shareholders are treated fairly in the event of a takeover bid for Osisko's common shares and that Osisko's Board of Directors and shareholders will have adequate time to evaluate any unsolicited takeover bid and, if appropriate, to evaluate and pursue other alternatives to maximize shareholder value.

The Plan was not adopted in response to any actual or threatened takeover bid or other proposal from a third party to acquire control of Osisko.

In accordance with regulatory requirements, the Plan was approved by 94.1% of the shareholders present and entitled to vote at the Company's Annual and Special Shareholders Meeting held on June 30, 2010 at the Canadian Malartic Site.

Highlights from the Company's financial position are as follows (in millions of dollars):

-----------------------------------------------------------------
                                June 30, 2010   December 31, 2009
-----------------------------------------------------------------
Cash Position(1)                        580.9               790.2
Working Capital                         560.9               760.4
Total Assets                          1,755.4             1,338.8
Shareholders' Equity                  1,410.9             1,112.3
-----------------------------------------------------------------
(1) Includes Cash and Cash equivalents, Short-term investments, Restricted
cash and Cash collateral.

The financial statements and Management Discussion and Analysis for the period ended June 30, 2010, will be filed on SEDAR by August 15, 2010.

Osisko Mining Corporation is currently developing the Canadian Malartic gold deposit and evaluating adjacent areas for a large-scale open pit, bulk-tonnage mining operation. The Company is well-funded with approximately $581 million on hand.

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.

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 the Corporation 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' and similar expressions, or that events or conditions 'will', 'would', 'may', 'could' or 'should' occur. Although the Corporation 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 (i) to put the Canadian Malartic Project into commercial production, or (ii) to complete the acquisition of Brett Resources Inc., 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 mining development and mill production personnel, results of exploration and development activities, the Corporation's limited experience with production and development stage mining operations, uninsured risks, regulatory changes, defects in title, availability of 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 the Corporation's most recent Annual Information Form filed on SEDAR, which also provides additional general assumptions in connection with these statements. The Corporation cautions that the foregoing list of important factors is not exhaustive. Investors and others who base themselves on the Corporation's forward-looking statements should carefully consider the above factors as well as the uncertainties they represent and the risk they entail. The Corporation 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

Contacts:

John Burzynski

Vice-President Corporate Development

416-363-8653
www.osisko.com


Sylvie Prud'homme

Investor Relations

514-735-7131

Toll Free: 1-888-674-7563