Production of 36,440 Ounces of Gold in Month of October

(Montreal, November 12, 2012) Osisko Mining Corporation (the “Company” or “Osisko”) (OSK: TSX, EWX: Deutsche Boerse) is pleased to report that it has achieved a record monthly throughput at its flagship Canadian Malartic Mine in the month of October. The mill processed a new record of 1,530,195 tonnes in the month of October, producing 36,440 ounces of gold in the month. Production statistics for October are listed below:

• Monthly gold production of 36,440 ounces
• Record monthly mill throughput of 1,530,195 tonnes
• Record average daily throughput (based on 31 days of operation) of 49,361 tonnes per day
• Average grade milled of 0.833 g/t Au
• Average recovery of 88.9%

November Throughput Preview
Crushing and milling throughputs have continued to improve towards and beyond design rates in the early part of November. Canadian Malartic’s nameplate throughput target of 55,000 tonnes per day was consistently exceeded over the first four days of November, with another new record one-day processing rate of 58,476 tonnes being achieved on November 4th. Average mill throughput in the first eight days of the current month averaged 52,853 tonnes per day. Installation of the second pebble crusher is currently planned for the next scheduled mill maintenance shut-down in December or January.

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 Chief Operating Officer 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.