Osisko Announces an Increase in Caterpillar Lease Financing Facility

MONTREAL, QUEBEC--(Marketwire - Aug. 31, 2011) - Osisko Mining Corporation ("Osisko")(TSX:OSK)(FRANKFURT:EWX) is pleased to announce that it has entered into an agreement with Caterpillar Financial ("Cat Financial") to increase its equipment leasing facility by US $56.3 million. The facility will be used to acquire additional mobile mining equipment fleet to develop the Canadian Malartic Mine and the Barnat gold deposit.

Sean Roosen, President and Chief Executive Officer, noted: "We are very pleased with the support from Cat Financial, one of our key financial partners, as we continue to develop our flagship Canadian Malartic operations."

The funding will be utilized through the purchase of three additional loading units, nine Cat 793F haulage trucks and other ancillary Cat equipment from Hewitt Equipment, which will be delivered in 2011 and 2012.

Terms and conditions of the lease credit facility are similar to the facilities currently in place.

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. Canadian Malartic's production is 100% unhedged.

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, including, without limitation, increasing of throughput at the mill to achieve design capacity, improving mill feed grade, maintaining recovery rates, increasing gold production and developing the Barnat gold deposit. Although the Corporation believes the expectations expressed in such forward-looking statements are based on reasonable assumptions, including, without limitation that the diligent ongoing optimizing of its operations 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,, the Corporation's limited experience with production and development stage mining operations, uninsured risks, regulatory changes or sanctions, defects in titles, 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 costs, 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.