MONTREAL, QUEBEC--(Marketwire - Aug. 11, 2011) - Osisko Mining Corporation (the "Company" or "Osisko") (TSX:OSK)(FRANKFURT:EWX) is pleased to report its review of activities and financial results for the quarter ended June 30, 2011.

Highlights

• Commencement of commercial production at Canadian Malartic on May 19, 2011
• Gold production of 46,605 ounces
• Continued progress in mill and mine ramp up
• Mine operating earnings of $1.6 million
• Loss of $23.8 million
• Withdrawal from Duparquet Project

The Canadian Malartic Mine successfully commenced commercial production on May 19, 2011, approximately six years after the first drilling conducted by Osisko at Malartic in March 2005. Commercial production was established on the first day of a 30-day period during which the mill processed 60% or better than the mill design capacity of 55,000 tonnes per day. Since introduction of ore in March, the ramp up has been successful despite the stops and starts that are normally experienced during the initial phase of a mining operation.

Sean Roosen, President and Chief Executive Officer commenting on the second quarter activities: "We are extremely proud of our team's efforts in rapidly moving Canadian Malartic from an exploration project to a producer, particularly considering the major challenges of developing a $1 billion project in an urban area."

The Canadian Malartic operations are expected to produce between 235,000 and 245,000 ounces of gold during the second semester of 2011 at an estimated cash cost of between $675-$775 per ounce. The progression is anticipated to continue in 2012 with the mine producing approximately 700,000 ounces at an estimated cash cost of $450-$500 per ounce.

Sean Roosen commenting on the forecast: "We are aiming to produce one million ounces over the next 18 months in a very favorable gold market. The expected strong margins should result in a payback of the project in slightly less than two years".

The Canadian Malartic Mine generated a $1.6 million profit during its initial 43-day operating period from the sale of 8,300 ounces. The remaining ounces produced during commercial production are in the circuit inventory. For the second quarter, Osisko incurred a loss of $23.8 million ($0.06 per share) due mainly to the write-off of Duparquet Project ($10.9 million), higher administrative costs, and expensed finance costs now that the Canadian Malartic Mine is in commercial production. The second quarter loss in 2010 amounted to $10.2 million ($0.03 per share). There were no mining operations prior to May 2011.

For the year-to-date, the loss totaled $29.1 million ($0.08 per share) compared to a loss of $10.7 million ($0.03 per share) in the corresponding period in 2010.

Canadian Malartic Mine

The Canadian Malartic Mine produced 46,605 ounces of gold in the second quarter from the treatment of 1.5 million tonnes of ore. Ore was first introduced late in March. Production statistics for the quarter are as follows:

	Pre-Production	Production	Total
Ore Tonnes Mined (t)	866,947	829,419	1,696,366
Tonnes Milled (t)	1,010,413	1,470,783	2,481,196
Grade (g/t Au)	0.69	0.65	0.67
Recovery (%)	87.4	88.0	87.8
Ounces Produced (oz)	19,505	27,100	46,605
Cash Cost per Ounce ($)	N/A	1,094	N/A

The higher production costs are attributable to initial low grade material, normal inefficiencies experienced during a ramp up period, and industry-wide inflationary pressures.

The mine generated an operating profit of $1.6 million from the sale of 8,300 ounces. The remaining ounces are categorized in inventory. Prior to commercial production, the Company incurred a loss during the commissioning period which was capitalized.

The mine operating statement for the production period is as follows:

	($000)
Gold Revenues	12,429
Operating Costs	26,860
Stockpile Costs	2,406
Total	29,266
Royalties and Refining	610
Depreciation	4,959
Total Costs	34,835
Less Inventory	(24,040)
Total Production Costs	10,795
Net Mining Profit	1,634

The mining activities have been affected by the delays in the construction of the green wall separating the mine and the residential area, the feedstock area for the wall construction, the noise levels of the mining operations and to a lesser extent the accelerated completion of the project, three months ahead of schedule. These factors necessitated earlier access to lower grade material than modeled in the feasibility, and the grade of ore treated is expected to increase throughout the second semester. Lower grade material has a significant negative impact on the unit costs. It is important to note however, that the mining grades are conforming to the reserve block model (+2% average variation), validating the extensive drilling program conducted to establish the mining reserves and plan.

The mill continues its ramp up process with scheduled shut downs for verifications, repairs and modifications. The operating statistics are as follows:

	Total Available Hours	Operating Hours	%	Tonnage (t)	Tonnes/ Hour	Tonnes/ per Calendar Day
April	720	468	65	465,900	995	15,530
May	744	646	87	892,553	1,382	28,792
June	720	679	94	1,122,742	1,654	37,425
July*	744	595	80	1,006,497	1,691	32,468
August (7 days )	168	151	90	271,962	1,800	38,852

* Three full days of shut down for SAG mill liner change.

A new daily throughput record of 47,485 tonnes processed was established on August 7, 2011.

The ramp up period has demonstrated that the rock hardness is as anticipated and the crusher and ball mills are performing better than their design criteria. The ramp up has also shown that the ore's SAG impact breakage index has demonstrated lower SAG grindability. The addition of a pre-crush circuit will allow for throughput expansion to 60,000+ tpd. The units have been ordered and will be available in early 2012, with the project costs estimated at $32 million. A portable crushing unit has been installed to increase the crushing capacity in the meantime.

Exploration and Development

The Company continues to aggressively pursue growth of reserve and resource base through intensive drilling programs around the Canadian Malartic Mine, at its Hammond Reef Project and on various grass-roots projects in Eastern Canada. A total of 88,336 metres (341 holes) were drilled during the second quarter, mostly from the definition drill program at Hammond Reef.

Following an evaluation of the results from its $15 million exploration program at Duparquet, the Company decided to serve notice to Clifton Star Resources that it was withdrawing from its joint venture program. As a result, a write-off of $10.9 million was recorded in the second quarter.

Second Quarter 2011 Results Conference Call

Osisko will host a conference call on Friday, August 12 at 10:00 AM EDT, where senior management will discuss the financial results and provide an update of the Company's activities. Those interested in participating in the conference call should dial in at 416-981-9000 (Toronto local and international), or 1-800-755-1805 (North American toll free). An operator will direct participants to the call. The call will be retransmitted for 14 days with the following dial in number: 416-626-4100 or Toll-free 1-800-558-5253, access code 21534865.

Highlights from the Company's financial position are as follows (in millions of dollars):

	June 30, 2011	December 31, 2010(1)
Cash Position(2)	175.7	397.9
Working Capital	101.5	282.9
Total Assets	1,951.4	1,958.9
Total Debt	289.4	287.9
Shareholders' Equity	1,586.6	1,594.0

(1) Revised under IFRS

(2) Includes Cash and Cash equivalents, Short-term investments and Restricted cash.

The unaudited condensed interim consolidated financial statements and Management Discussion and Analysis for the period ended June 30, 2011 will be filed on SEDAR on August 15, 2011.

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, P. 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.

Osisko Mining Corporation

Consolidated Statements of Income (Loss)

For the three and six months ended June 30, 2011 and 2010

(Unaudited)

(tabular amounts expressed in thousands of Canadian dollars)

		Three months ended June 30,				Six months ended June 30,
		2011		2010		2011		2010
		$		$		$		$
Revenues		12,429		-		12,429		-
Mine operating costs
	Production costs	(9,398	)	-		(9,398	)	-
	Royalties	(159	)	-		(159	)	-
	Depreciation and depletion	(1,238	)	-		(1,238	)	-
Earnings from mine operations		1,634		-		1,634		-
	General and administrative expenses	(12,018	)	(5,444	)	(18,194	)	(9,991	)
	Exploration and corporate development expenses	(11,811	)	(210	)	(13,160	)	(571	)
	Other expenses	-		-		(485	)	-
Loss from operations		(22,195	)	(5,654	)	(30,205	)	(10,562	)
	Interest income	601		652		1,510		1,301
	Finance costs	(3,771	)	-		(3,771	)	-
	Foreign exchange gain (loss)	466		(2,803	)	1,514		92
	Share of loss of associate	(345	)	-		(451	)	(198	)
	Other gains (losses)	1,984		(2,088	)	3,292		(1,366	)
Loss before income taxes		(23,260	)	(9,893	)	(28,111	)	(10,733	)
	Income tax expense	(566	)	(295	)	(996	)	(6	)
Loss for the period		(23,826	)	(10,188	)	(29,107	)	(10,739	)
Attributable to:
	Osisko Mining Corporation	(23,826	)	(10,123	)	(29,107	)	(10,674	)
	Non-controlling interests	-		(65	)	-		(65	)
		(23,826	)	(10,188	)	(29,107	)	(10,739	)
Loss per share
	Basic and diluted	(0.06	)	(0.03	)	(0.08	)	(0.03	)

Osisko Mining Corporation

Consolidated Balance Sheets

(Unaudited)

(tabular amounts expressed in thousands of Canadian dollars)

		June 30, 2011		December 31, 2010
		$		$
Assets
Current assets
	Cash and cash equivalents	150,976		358,493
	Short-term investments	3,045		17,068
	Restricted cash	7,220		11,176
	Accounts receivable	38,243		30,731
	Mining taxes receivable	-		2,058
	Inventories	42,077		-
	Other current assets	8,011		7,329
		249,572		426,855
Non-current assets
	Restricted cash	14,468		11,202
	Investment in an associate	1,707		2,158
	Other investments	34,064		40,851
	Property, plant and equipment	1,651,546		1,477,818
		1,951,357		1,958,884
Liabilities
Current liabilities
	Accounts payable and accrued liabilities	70,821		73,519
	Current portion of long-term debt	77,207		70,405
		148,028		143,924
Non-current liabilities
	Long-term debt	212,172		217,481
	Provisions	4,572		3,494
		364,772		364,899
Equity attributable to Osisko Mining Corporation shareholders
	Share capital	1,627,120		1,606,051
	Warrants	13,166		13,166
	Contributed surplus	50,465		43,390
	Equity component of convertible debenture	8,005		8,005
	Accumulated other comprehensive income	4,582		11,019
	Deficit	(116,753	)	(87,646	)
		1,586,585		1,593,985
		1,951,357		1,958,884

Osisko Mining Corporation

Consolidated Statements of Cash Flows

For the six months ended June 30, 2011 and 2010

(Unaudited)

(tabular amounts expressed in thousands of Canadian dollars)

			2011		2010
			$		$
Operating activities
	Loss for the period		(29,107	)	(10,739	)
	Adjustments for:
		Interest income	(1,510	)	(1,301	)
		Share-based compensation	5,453		2,815
		Depreciation	1,574		186
		Finance costs	1,292		-
		Write-off of property, plant and equipment	11,381		-
		Unrealized foreign exchange loss (gain)	(2,009	)	10
		Share of loss of associate	451		198
		Loss (gain) on sale of available-for-sale financial assets	(5,017	)	396
		Unrealized net loss on financial assets at fair value through profit and loss	4,471		1,919
		Deferred gain - premium on flow-through shares	(2,228	)	(949	)
		Provisions	135		-
		Deferred tax expense	996		6
		Other non-cash gain	(639	)	-
			(14,757	)	(7,459	)
	Change in non-cash working capital items		9,175		694
Net cash flows used in operating activities			(5,582	)	(6,765	)
Investing activities
	Net decrease in short-term investments		14,023		30,329
	Net decrease in restricted cash		690		1,575
	Decrease in cash collateral investments		-		2,851
	Acquisition of investments		(11,294	)	(24,447	)
	Proceeds on disposal of investments		11,834		3,891
	Property, plant and equipment, net of government credits		(237,023	)	(229,787	)
	Acquisition of assets		-		39,861
	Interest income		1,614		1,281
Net cash flows used in investing activities			(220,156	)	(174,446	)
Financing activities
	Debt issuance costs		(18	)	-
	Finance lease payments		(819	)	(7,322	)
	Long-term debt repayments		(833	)	-
	Issuance of common shares, net of issue expenses		19,891		13,994
Net cash flows generated from financing activities			18,221		6,672
Decrease in cash and cash equivalents			(207,517	)	(174,539	)
Cash and cash equivalents – beginning of period			358,493		673,777
Cash and cash equivalents – end of period			150,976		499,238

Cautionary Notes Concerning Estimates of Mineral Resources

This news release uses the terms measured, indicated and inferred resources as a relative measure of the level of confidence in the resource estimate. Readers are cautioned that mineral resources are not economic mineral reserves and that the economic viability of resources that are not mineral reserves has not been demonstrated. In addition, inferred resources are considered too geologically speculative to have any economic considerations applied to them. It cannot be assumed that all or any part of an inferred mineral resource will ever be upgraded to a higher category. Under Canadian rules, estimates of inferred mineral resources may not form the basis of feasibility or pre-feasibility studies or economic studies except for Preliminary Assessment as defined under NI 43-101. Readers are cautioned not to assume that that further work will lead to mineral reserves that can be mined economically.

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 the Corporation 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" and similar expressions, or that events or conditions "will", "would", "may", "could" or "should" occur. Although the Corporation believes the expectations expressed in such forward-looking statements are based on reasonable assumptions, including, without limitation that all technical, economical and financial conditions will be met in order to put the Canadian Malartic Project into commercial production, 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 mining development and mill production personnel, results of exploration and development activities, the Corporation's limited experience with production and development stage mining operations, uninsured risks, regulatory changes, defects in title, availability of materials and equipment, timeliness of government approvals, actual performance of facilities, equipment and processes relative to specifications and expectations, unanticipated environmental impacts on operations costs, continued availability of capital and financing and general economic, market or business conditions. These factors are discussed in greater detail in the Corporation's most recent Annual Information Form filed on SEDAR, which also provides additional general assumptions in connection with these statements. The Corporation cautions that the foregoing list of important factors is not exhaustive. Investors and others who base themselves on the Corporation's forward-looking statements should carefully consider the above factors as well as the uncertainties they represent and the risk they entail. The Corporation 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.