Osisko Brings First Half of Secondary Crusher Online

MONTREAL, QUEBEC--(Marketwire - March 12, 2012) - Osisko Mining Corporation (the "Company" or "Osisko") (TSX:OSK)(FRANKFURT:EWX) is pleased to report that construction and installation of the first of two cone crushers in the secondary crushing facility has been successfully completed.

Commissioning of crusher number one at the secondary crushing facility is now underway. Crusher number two of the secondary crushing facility will be added upon arrival at site, which is still anticipated to be on schedule this coming June. A planned maintenance shut-down of the mill was also completed on Friday, with a liner change out in the SAG mill. The mill and the new secondary crusher line have been started and are ramping up towards their target of 50,000 tonnes per day, as the manufacturer's standard start-up test protocols are being completed.

Osisko President and CEO Sean Roosen commented: "The addition of the new cone crusher sets the stage for us to pursue the ramp up to 50,000 tonnes per day at the Canadian Malartic mill, which has a name plate design capacity of 55,000 tonnes per day. Construction and commissioning has gone very well with the mild winter we had on site. We want to congratulate the team including Osisko workers and contractors for completing the construction and installation ahead of schedule executing the build with no time lost accidents."

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 COO 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.

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, the successful ramping up of the mill and the new secondary crusher line towards their target capacity, timely installation of the second crusher of the secondary crushing facility, and increasing of throughput at the mill to achieve design capacity at its Canadian Malartic Mine in compliance with noise regulations. Although Osisko 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 at Canadian Malartic mine 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 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.