Osisko Provides Update on Construction and Development Progress at Canadian Malartic

MONTREAL, QUEBEC--(Marketwire - Dec. 21, 2009) - Osisko Mining Corporation ("Osisko") (TSX:OSK)(FRANKFURT:EWX) is pleased to provide a report on the progress of the construction and development program at Canadian Malartic.

Following the approval received from the Conseil des ministres du Quebec for the Canadian Malartic Project, Osisko's project team initiated construction activities on August 27, 2009. Today, after 116 days, construction startup is 100 percent complete and on time. Due to very good weather conditions, the relocation program advanced to a 95% rate of completion. The construction program is advancing as planned, with approximately CA$600 million of contracts having been executed or let out to date. Principal highlights of the work completed or underway are as follows:

Administration/Truck Shop Facility

An accelerated construction program was initiated in late August for the main administration and truck shop facility. This building has a surface area of 8,500 square metres. To date, all foundation, steel erection and metal siding work have been completed. Interior finishing will be continued in the first quarter of 2010.

120kV Power line

Hydro-Quebec has received the necessary authorizations to initiate construction of the 120kV electrical line. Bush clearing activities are currently underway, and erection work on the 19 km power line will start in the first quarter of 2010.

Main Electrical Sub-station

Concrete work and erection of steel structure has been completed, and the reception at site of the three transformers is currently in progress.

Ancillary Facilities

Construction of ancillary facilities (security building, fuel depot) is in progress. The construction administration facility has been completed and is now fully functional.

Gyratory Crusher

Key activities have been initiated at the gyratory crusher site, including mass backfill work for the support of the principal conveyor work, and excavation to bedrock for the construction of the crusher building. Concrete work has commenced and will continue through to the second quarter of 2010.

Mill

Concrete work on the mill building and the pouring of the foundations for the SAG and ball mills are progressing rapidly. To date, more than 20,000 cubic metres of concrete have been poured in the mill area alone, representing 80% of the planned volume for the mill construction.

Steel erection for the main mill building was initiated on November 16 and is expected to be completed during the second quarter of 2010.

The mechanical installation activities of the mill will commence in the second quarter of 2010. The SAG mill and two of the three ball mills have been received at site. Delivery of the third ball mill is expected during the second quarter of 2010.

Leach Tanks

Erection of the leach tanks was initiated in September and is progressing. The Project requires the 20 tanks with a capacity of 3,000 cubic metres.

Polishing Pond

Clearing activities and road access work have been completed. In addition, construction of the main dams "A" and "B" are underway. A total of five dams will be constructed for the polishing pond.

Mining

Tree clearing work has been completed for the Canadian Malartic pit. Drainage work and overburden activities have been initiated.

The Company has accepted the delivery of one O&K RH340B electrical shovel and three 240-tonne 793F Caterpillar trucks, as well as additional ancillary support equipment.

Relocation

Relocation activities have progressed to near completion. Main activities included:

- Relocation of 140 homes to new sector;

- Construction and turnover to authorities of the new elementary school, day care facility, adult training centre, and low cost housing units. It is anticipated that construction of the community centre/auditorium will be completed in January and the elderly health care facility in May 2010.

- Significant advancement has been made on the closure of the southern sector with the demolishing of institutional and non-relocated residential units.

Human Resources

Osisko continues to recruit its workforce for the supervision of the construction program and the future mining activities. The Company has received more than 10,000 resumes for potential permanent positions.

Safety

The Company is very proud of achieving 500,000 hours without a lost time accident at the end of November.

Cost and Commitments

To the end of November, the Company had invested CA$340 million, representing 36.5% of the CA$931 million capital budget. In addition, the Company has entered into commitments for approximately $245 million. The Company anticipates that the Project will be completed within the initial budget estimate.

Sean Roosen, President and Chief Executive Officer, commenting on the Project advancement noted: "We are very pleased with the progress at Canadian Malartic. Our rapid pace is the result of the advanced stage of our detailed engineering, sound planning by our highly experienced construction management team, and great collaboration with all stakeholders including suppliers and contractors. We greatly appreciate the efforts of all those involved and are looking forward to their continued focus in 2010 and early 2011 to complete the Project on time and on budget."

About Osisko

Osisko Mining Corporation is currently developing the Canadian Malartic gold deposit and adjacent mineralized zones into a large-scale open pit, bulk-tonnage mining operation. The Company is well-funded with $825 M in cash resources and is carrying out an aggressive mine development, reserve definition and exploration campaign. The Canadian Malartic deposit currently represents one the biggest gold reserves in Canada for a single deposit, and is still growing through ongoing drilling on new mineralized zones. Current reserves for the Canadian Malartic property are 6.28 million ounces with 183.3 Mt @ 1.07 g/t Au (proven reserves: 5.16 Mt @ 1.14 g/t Au, probable reserves: 178.2 Mt @ 1.06 g/t).

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", "scheduled" 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 to put the Canadian Malartic Project into commercial production, 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 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 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 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 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.

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Osisko Provides Update on Construction and Development Progress at Canadian Malartic