(Montreal, April 8,
2014) Osisko
Mining Corporation (the “Company” or “Osisko”) (OSK: TSX, EWX: Deutsche Boerse)
is pleased to report that following record production in Q4 2013 of 137,321
ounces gold, Osisko’s flagship Canadian Malartic mine has again achieved record
gold production of 140,029 ounces gold in Q1 2014.  Production statistics
for the quarter and the month of March are presented below.  A conference
call will be held this morning at 9:00 am to discuss the Q1 production results
(details provided below).

First Quarter
Production Statistics

• Record
  production of 140,029 ounces gold
• Average
  grade milled of 1.13 g/t Au
• Average
  recovery of 88.2%
• Mill
  throughput of 4,363,365 tonnes

March Production
Statistics

• Production
  of 43,764 ounces gold
• Record
  average grade milled of 1.14 g/t Au
• Average
  recovery of 88.2%
• Monthly
  mill throughput of 1,349,619 tonnes

Since commencement of
milling operations in April 2011, Canadian Malartic has produced 1,203,921
ounces of gold.

Osisko ended the current
quarter with an estimated $258 million of cash resources¹ on
hand.

Cash costs per ounce in Q4
2013 were US$679 (C$713).  Following Q4, in January 2014, Canadian
Malartic achieved record monthly production of 50,111 ounces at cash costs²
of US$613 (C$670), followed by record daily production of 1,648 ounces
gold in February and cash costs² of US$555 (C$613).  Cash costs
per ounce for 2014 are estimated at between US$527 (C$580) and US$577 (C$635),
a 24% to 16% reduction in costs from 2013.

Mill throughput is expected
to stabilize at approximately 55,000 tonnes per day in 2014 with the completion
of optimization programs currently in progress. Together with increased
contribution from higher grade material in the now accessible northern pit
wall, it is anticipated that gold production for the current year will increase
to between 525,000 to 575,000 ounces, an increase of 11% to 21% over record 2013
production of 475,277 ounces gold.

Canadian Malartic has
proven & probable in-pit reserves of 9.37 million ounces, with a mine life
of 14.2 years based on a 55,000 tonne per day (tpd) milling rate.  Average
gold production is forecast at 610,000 ounces per year over the next five years
(2014 – 2018) at cash costs of US$516 per ounce, with an average of 597,000
ounces per year gold production over life of mine at cash costs of US$525 per
ounce.  The mine is expected to have an average head grade of 1.09 g/t Au
over the next five years, and 1.03 g/t Au over the mine life, with average
metallurgical recovery of 89.2% over the mine life.

Sean Roosen, President and
CEO of Osisko stated:  “Canadian Malartic is continuing on its record
setting pace for 2014.  March was another strong month of gold production,
despite an unanticipated four day shutdown of the mill circuit to repair loose
liners in the SAG mill.  Despite this, we have achieved another record for
quarterly gold production, again underlining Canadian Malartic’s value to all
shareholders with its top class gold production and strong cash flow.

Last week, Osisko announced
a partnership agreement (the “Arrangement”) with Yamana Gold, unanimously
supported by Osisko’s board of directors which determined that the Arrangement
is in the best interests of Osisko and its shareholders and will recommend that
Osisko shareholders vote in favour of the Arrangement.

I would like to remind
shareholders of the unanimous recommendation of Osisko’s Board of Directors to
shareholders that you reject Goldcorp’s inadequate hostile offer, and not to
tender your shares to their bid.”

Reject the
Inadequate Goldcorp Offer

As previously disclosed,
the Osisko Board of Directors has unanimously recommended that Osisko shareholders
reject
the hostile take-over bid initiated by Goldcorp and not tender their
Osisko shares to the Goldcorp offer. The Osisko Board determined that the
Goldcorp offer fails to adequately compensate Osisko shareholders for, among
others things, the strategic value of Osisko’s world-class asset base, the
significant upside potential of Osisko’s Canadian Malartic Mine, or the
increased risk inherent in Goldcorp common shares. The full basis for the
Osisko Board’s recommendation is available in a Directors’ Circular, a copy of
which is available online at www.osisko.com.

Shareholders who have
questions or who may have already tendered their shares to the Goldcorp Offer
and wish to withdraw them, may do so by contacting our Information Agent,
Laurel Hill Advisory Group at:

North American Toll
Free:  1-877-452-7184

Banks, Brokers or
collect calls:  416-304-2011

Email: [email protected]

Conference Call
Information

Osisko will host a
conference call on Tuesday, April 8, 2014 at 9:00 am EDT, where Osisko senior
management will discuss the Q1 production details. Those interested in
participating in the conference call should dial in approximately five to ten
minutes before the start of the conference to allow ample time to access at
(416) 981-9000 (Toronto local and international), or 1-800-757-8521 (North
American toll free). An operator will direct participants to the call.

The conference call replay
will be available from 11:00 EDT on April 8, 2014 until 11:59 EDT on April 22,
2014 with the following dial in number: (416) 626-4100 or toll-free 1
800-558-5253, access code 21713833.

About Osisko Mining
Corporation

Osisko Mining Corporation
operates the Canadian Malartic Gold Mine in Malartic, Québec and is pursuing
exploration on a number of properties in Ontario and Mexico.

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.

Reserve estimates
using base case US$1,300 engineered pit design

with lower cut-off
grade of 0.33 g/t Au 

*Barnat and Jeffrey
represent portions owned by Osisko

For further information on
Canadian Malartic, please see at www.osisko.com
or at www.sedar.com “Updated resource and reserve
estimates for the Canadian Malartic Project Malartic, Quebec”,
dated May 10, 2011 and prepared by Belzile Solutions Inc. and G Mining Services
Inc., as updated by press releases dated February 19, 2013 and March 12, 2014

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 Osisko 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”, “scheduled” and similar
expressions, or that events or conditions “will”, “would”, “may”, “could” or
“should” occur including, without limitation, the satisfaction of all
technical, economical, regulatory and financial conditions in order to complete
the Arrangement between Osisko and Yamana, the stabilization of mill
throughput, the completion of optimization programs, the decrease of costs and
increase of grade and gold production, Osisko’s view on the quality and the
potential of its Canadian Malartic asset and on Goldcorp common shares and
offer, and that mining of the deposits identified in this press release will be
executed timely and fully, and will return values identified in the foregoing
estimate. Although Osisko believes the expectations expressed in such
forward-looking statements are based on reasonable assumptions, 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 consultants, mining
development and construction personnel, results of exploration and development
activities, Osisko’s limited experience with production and mining operations,
uninsured risks, regulatory framework and changes, defects in title,
availability of personnel, materials and equipment, timeliness of government
approvals, actual performance of facilities, equipment and processes relative
to specifications and expectations, unanticipated environmental impacts on
operations market prices, continued availability of capital and financing and
general economic, market or business conditions. These factors are discussed in
greater detail in Osisko’s most recent Annual Information Form and in the most
recent Management Discussion and Analysis filed on SEDAR, which also provide
additional general assumptions in connection with these statements. Osisko
cautions that the foregoing list of important factors is not exhaustive.
Investors and others who base themselves on forward-looking statements should
carefully consider the above factors as well as the uncertainties they
represent and the risk they entail. Osisko 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 and such
forward-looking statements included in this press release should not be unduly
relied upon. These statements speak only as of the date of this press release.

1 Includes cash and
cash equivalents and restricted cash

2
Non-IFRS financial performance measures have no standard definition under
IFRS.  Please refer to the 2013 Management and Discussion Analysis filed
on SEDAR for a description of Non-IFRS financial performance measures