Mr. John Burzynski reports

OSISKO INTERSECTS 71.4 G/T AU OVER 5.4 METRES AT WINDFALL

Osisko Mining Inc. has released new results from the continuing drill program at its 100-per-cent-owned Windfall Lake gold project located in Urban township, Quebec. The current 400,000-metre drill program combines definition drilling above the Red Dog intrusion, expansion drilling above and below Red Dog, expansion drilling to the northeast of the main deposit, and exploration drilling on the greater deposit and Urban-Barry project area. New analytical results from four drill holes focused on the Lynx zone discovery are reported in this release, with significant assay results presented in the associated table.

New results include: 71.4 grams per tonne gold over 5.4 metres (uncut) in OSK-W-17-792; 57.0 g/t Au over 3.6 metres (uncut) and 21.1 g/t Au over 3.7 metres in OSK-W-17-788; and 21.6 g/t Au over 7.9 metres (uncut) in OSK-W-17-779.

Hole               From       To       Interval         Au uncut        Au cut to 100 g/t
No.                 (m)      (m)            (m)            (g/t)                    (g/t)

OSK-W-17-779      268.0    275.9            7.9             21.6                     16.9
including         274.3    275.0            0.7              154                      100
                  282.0    284.5            2.5             18.1
                  298.0    300.7            2.7             15.6
including         298.9    300.0            1.1             33.2
OSK-W-17-788      236.4    240.0            3.6             57.0                     36.6
including         236.4    236.9            0.5              153                      100
and               239.0    239.5            0.5              194                      100
                  245.0    248.7            3.7             21.1
including         247.8    248.7            0.9             54.8
OSK-W-17-790      261.6    265.2            3.6             11.3
including         261.6    262.3            0.7             28.7
and               264.7    265.2            0.5             39.9
OSK-W-17-790      269.5    272.5            3.0             4.32
including         269.5    270.6            1.1             10.1
OSK-W-17-792      313.3    318.7            5.4             71.4                     42.5
including         315.6    316.7            1.1            242.0                      100

Notes                                                                     
(1) True widths currently undetermined. See quality control.        
(2) Definitions: PRSB -- pyrite-rich silicified bands. CV -- crustiform veins.
                                                                           

The Lynx zone is a recently discovered corridor of gold mineralization located to the east of the main Windfall deposit mineralized zones. To date it has been intersected at shallow depths (60 metres) and up to 330 metres below surface, over a strike length of over 300 metres and remains open laterally and at depth. The Lynx zone was discovered as a result of the stepout drilling program which was designed to test an east-northeast magnetic low corridor containing altered porphyry dikes similar to those previously defined in the main deposit area. Mineralization consists of a series of crustiform veins and heavily silicified, pyrite-rich alteration bands hosted in strongly silicified and sericitized rhyolite and porphyry dikes. The veins and silicified bands are intersected at various angles, including low core angles, suggesting they may represent a vein network. Additional drilling will be conducted to the southeast to further evaluate the abundance and true thickness of the veins and silicified bands. True thicknesses of reported intersections are presently unknown.

OSK-W-17-779 tested the Lynx corridor and intersected 16.9 g/t Au over 7.9 metres (21.7 g/t Au over 7.9 metres uncut) followed by 18.1 g/t over 2.5 metres and 15.6 g/t Au over 2.7 metres in crustiform veins containing 1 to 5 per cent pyrite and local visible gold. The veins are hosted in silicified and sericitized rhyolite. Veining was generally intersected at 20 to 40 degrees to the axis of the core and the true width of the vein system is undetermined at this time.

OSK-W-17-788 returned 36.6 g/t Au over 3.6 metres (57.0 g/t Au over 3.6 metres uncut) followed by 21.1 g/t Au over 3.7 metres in a series of subparallel highly silicified pyrite-rich alteration bands with local visible gold hosted in a sericitized and silicified rhyolite containing 1 to 5 per cent pyrite stringers and disseminations.

OSK-W-17-790 intersected 11.3 g/t Au over 3.6 metres in a series of highly silicified pyrite-rich alteration bands hosted in a sericitized and silicified porphyry dike containing 3 to 5 per cent pyrite stringers and disseminations.

OSK-W-17-792 averaged 42.5 g/t Au over 5.4 metres (71.4 g/t Au over 5.4 metres uncut) in a series of silicified pyrite-rich alteration bands containing 5 to 20 per cent pyrite and local visible gold hosted in a sericitized and silicified rhyolite. This interval is located 40 metres above and 20 metres to the east of 11.3 g/t Au over 3.6 metres in OSK-W-17-790 described above.

Qualified person

The scientific and technical content of this news release has been reviewed, prepared and approved by Dr. Jean-Philippe Desrochers, PhD, PGeo, senior project manager of the Windfall Lake gold project, who is a qualified person as defined by National Instrument 43-101 -- standards of disclosure for mineral projects.

Quality control and reporting protocols

True widths of the new exploration intercepts below Red Dog reported in this press release have yet to be determined. Additional drilling is planned for the immediate area which will enable the true width determination. True widths of intercepts in the zones above the Red Dog are estimated at 65 to 80 per cent of the reported core length intervals. Assays are uncut except where indicated, and calculated intervals are reported over a minimum length of two metres using a lower cut-off of three g/t Au. All NQ core assays reported were obtained by either one-kilogram whole-rock metallic screen/fire assay or standard 50-gram fire assaying with AA (atomic absorption) or gravimetric finish at ALS Laboratories in Val d'Or, Que., or Sudbury, Ont. The one-kilogram metallic screen assay method is selected by the geologist when samples contain coarse gold or present a higher percentage of pyrite than surrounding intervals. All samples are also analyzed for multielements, including silver, using an aqua regia ICP-AES (inductively coupled plasma atomic emission spectroscopy) method at ALS Laboratories. Drill program design, quality assurance/quality control and interpretation of results are performed by qualified persons employing a quality assurance/quality control program consistent with National Instrument 43-101 and industry best practices. Standards and blanks are included with every 20 samples for quality assurance/quality control purposes by the corporation as well as the lab. Approximately 5 per cent of sample pulps are sent to secondary laboratories for check assays.

About the Windfall Lake gold deposit

The Windfall Lake gold deposit is located between Val d'Or and Chibougamau in the Abitibi region of Quebec, Canada. The current mineral resource comprises 2,762,000 tonnes at 8.42 g/t Au (748,000 ounces) in the indicated category and 3,512,000 tonnes at 7.62 g/t Au (860,000 ounces) in the inferred category (sourced from a technical report dated June 10, 2015, entitled "Preliminary economic assessment of the Windfall Lake gold property, Quebec, Canada," with an effective date of April 28, 2015, prepared in accordance with NI 43-101). The Windfall Lake gold deposit is currently one of the highest-grade resource-stage gold projects in Canada. The bulk of the mineralization occurs in the main zone, a southwest/northeast-trending zone of stacked mineralized lenses, measuring approximately 600 metres wide and at least 1,400 metres long. The deposit is well defined from surface to a depth of 500 metres, and remains open along strike and at depth. Mineralization has been identified only 30 metres from surface in some areas and as deep as 870 metres in others, with significant potential to extend mineralization up and down plunge and at depth.

About Osisko Mining Inc.

Osisko is a mineral exploration company focused on the acquisition, exploration and development of precious metal resource properties in Canada. Osisko holds a 100-per-cent interest in the high-grade Windfall Lake gold deposit located between Val d'Or and Chibougamau in Quebec and holds a 100-per-cent undivided interest in a large area of claims in the surrounding Urban Barry area (82,400 hectares), a 100-per-cent interest in the Marban project located in the heart of Quebec's prolific Abitibi gold mining district, and properties in the Larder Lake mining division in Northeast Ontario, including the Jonpol and Garrcon deposits on the Garrison property, the Buffonta past-producing mine, and the Gold Pike mine property. The corporation also holds interests and options in a number of additional properties in Northern Ontario.

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