Osisko Mining Corp.

Gold Production Forecast at 1.02M ounces over next 18 months

MONTREAL, QUEBEC -- (Marketwire) -- 04/28/11 -- Osisko Mining Corporation (TSX: OSK)(FRANKFURT: EWX) ('Osisko') is pleased to provide a revised summary of the annual mine production plan for its 100%-owned Canadian Malartic project. This new plan is based on the $US1000 gold reserve estimate of 10.71M ounces gold that was recently disclosed (see March 31, 2011 press release). G Mining Services of Montreal are the independent consultants for Osisko who have authorized the release of the following plan. Highlights include:

Total reserves up 19 percent

MONTREAL, QUEBEC -- (Marketwire) -- 03/31/11 -- Osisko Mining Corporation (TSX: OSK)(FRANKFURT: EWX) is pleased to provide an updated reserve and resource estimate for its 100%-owned Canadian Malartic project. This new estimate, calculated at US$1000 gold, combines the previously-reported US$825 reserves and resources of the Canadian Malartic (CM) and South Barnat deposits (see February 10 2010 press release) with new resources defined from the ongoing drill program, including the Barnat Extension and Gouldie Zones.

MONTREAL, QUEBEC -- (Marketwire) -- 02/28/11 -- Osisko Mining Corporation ('Osisko') (TSX: OSK)(FRANKFURT: EWX) and Golden Valley Mines Ltd. (TSX VENTURE: GZZ) are pleased to announce additional results from the 2010 drill program targeting the Jeffrey Zone on the Malartic CHL Property, currently under option from Abitibi Royalties Inc., a wholly-owned subsidiary of Golden Valley Mines Ltd., and located immediately

MONTREAL, QUEBEC -- (Marketwire) -- 02/24/11 -- Osisko Mining Corporation ('Osisko'), (TSX: OSK)(FRANKFURT: EWX) is pleased to announce initial results from the fall 2010 drilling program at the Hammond Reef gold project, located near Atikokan in western Ontario. The Hammond Reef project is 100 percent owned by Osisko Hammond Reef Gold Ltd., a wholly-owned subsidiary of Osisko. The fall 2010 program included 324