Osisko Corporate Update

MONTREAL, QUEBEC--(Marketwired - April 29, 2013) - The recent volatility in the gold price and financial markets has led Osisko Mining Corporation (the "Company" or "Osisko") (TSX:OSK)(FRANKFURT:EWX) to review its rate of discretionary spending in exploration and advancing new projects. As a result, the Company will be decreasing discretionary spending for 2013 by over $80 million.

Throughput and production at Canadian Malartic are progressing well and in accordance with expectations, as laid out in the Company's 2013 forecasts (see Osisko Press Release dated January 24, 2013).

The Company has had excellent productivity on current drilling programs and is now at a compilation and assessment phase concerning forward strategy on these projects. Osisko enjoys flexibility on its major projects, a benefit of being the sole owner, and thus can select the rate of execution of its investment programs without concern for compromising ownership rights.

UPPER BEAVER PROJECT

Work at Upper Beaver is focused on drilling deep holes to test extensions of known zones. The Company has completed approximately 29,290 meters of drilling since January 1, 2013. Over the next few months, work will be limited to completion of current holes and compiling information generated during the drilling phase to date.

The shaft collar work has recently been completed. Construction of the head frame and surface facilities will be delayed, as well as the shaft sinking. Osisko project personnel are reviewing opportunities to capture savings due to the recent slowdown in the mining sector. This reassessment period will result in a deferral of approximately $50 million of the planned Upper Beaver outlays for 2013.

REGIONAL EXPLORATION KIRKLAND LAKE

The Company has completed 31,750 meters on various regional targets in the Kirkland Lake - Larder camp. Drilling activities will be reduced to focus on compilation and assessment of the results.

HAMMOND REEF

Permitting and Environmental Impact Assessment (EIS/EA) work is progressing. The draft EIS/EA report was submitted on February 15, 2013. The five week comment period ended on April 5, 2013. Comments were received from Aboriginal groups, the public and the government review team and the Company is preparing its responses to the matters raised.

Osisko's Engineering and Construction group is reviewing various estimates in light of the recent changes in the marketplace and is seeking opportunities to reduce capital costs.

The level of expenditures at Hammond Reef is expected to be reduced by $3.5 million from the original 2013 budget.

No decision will be made to advance the Hammond Reef project further pending receipt of the final feasibility which is expected later this year.

MEXICO EXPLORATION

Phase One drilling on Osisko's grassroots exploration project in Mexico has been completed, and analytical results are still pending. The Company expects to reduce the budget for work planned for 2013 by approximately half, through reducing further drilling and general exploration reductions.

REDUCTION IN WORKFORCE COMPLEMENT

Modifications to the Company's exploration and advanced projects will result in Osisko reducing its workforce by approximately 6% over the next few months.

Mr. Sean Roosen, Osisko President and CEO commenting on the revised schedule and investment plan said: "In the current market conditions we will focus our efforts on Canadian Malartic. Our discretionary investment program has been modified as responsible corporate policy to take into account the recent decline in the gold price. Having full ownership of our major projects allows us to adapt our investment spend rate and preserve the free cash flow generated by our flagship Canadian Malartic Mine".