MONTREAL, QUEBEC -- (Marketwire) -- 05/17/12 -- Osisko Mining Corporation (the "Company" or "Osisko") (TSX:OSK)(FRANKFURT:EWX) is pleased to report that the Canadian Malartic mill has been returned to operational status as of 10 pm Wednesday evening. The grinding circuit is currently operating on a reduced basis using bypass feed with three of the four cyclone sets and two of three ball mills, as well as the SAG. Work is progressing on the repairs to the number 4 cyclone set, which is expected to be returned to operation within one weeks time. Recommissioning of the number 4 cyclone set will allow the third ball mill to be returned to operation. The primary and secondary crushers are undergoing scheduled maintenance and are expected to be returning to operation by Saturday.

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.