Osisko Reports New Results from Ongoing Drill Program at Windfall Lake Gold Project

Osisko Mining Inc. is pleased to announce new results from the ongoing drill program at its 100% owned Windfall Lake gold project located in the Urban Township, Québec. The current 150,000 metre drill program combines definition drilling above the Red Dog intrusion ("Red Dog"), expansion drilling above and below Red Dog and exploration drilling on the greater deposit and overall property area.

Significant new results include: 34.4 g/t Au over 5.7 metres (uncut) in DDH OSK-W-16-720; 13.8 g/t Au over 6.6 metres in DDH OSK-W-16-708-W2; 7.57 g/t Au over 7.70 metres in DDH OSK-W-16-706-W3; 11.8 g/t Au over 4.6 metres in DDH OSK-W-16-309-W3; and 9.45 g/t Au over 2.1 metres in DDH OSK-W-16-727.

The new results demonstrate the continuity of the gold mineralization and the high potential for significant new mineralization near the known Windfall mineral inventory through continued definition and exploratory drilling, specifically in the eastern extension of the deposit and below the Red Dog intrusion. Six drills are currently active on site, and an additional four drills will be added to the program in the coming weeks. A total of seven new drill holes are reported in this release, and with significant results presented in the table below.

Notes:
(1) For complete drilling results please see www.osiskomining.com.
(2) True widths are estimated at 65-80% of the reported core length interval. See "Quality Control" below.
(3) High grade values cut to 100 g/t Au

Drill Hole Collar Coordinates

DDH OSK-W-16-720 confirms the NE extension of the Caribou corridor with 34.4 g/t Au over 5.7 metres (20.9 g/t Au over 5.7 metres cut to 100 g/t). This new portion of the Caribou Zone was first intersected with DDH OSK-16-642 (10.0 g/t Au over 2.6 metres, Osisko press release dated May 12, 2016) located 75 metres down-plunge to the ENE. This new extension remains open in its down-plunge and down-dip extensions and is a further illustration of the good potential to discover additional gold zones in the proximity of known zones.

DDH OSK-W-16-724 tested the down-plunge extension of gold mineralization 150 metres to the ENE of known zones. The hole intersected 5.06 g/t Au over 3.3 metres in the down-plunge extension of the Caribou N2 Zone. Gold mineralization is hosted in an altered porphyry dyke containing 3-15% pyrite stringers and disseminations. This intercept shows the gold mineralization in the Caribou Corridor extends for more than 800 metres laterally and confirms the Main Zone is open in its down-plunge extension.

DDH OSK-W-16-726 tested the Underdog Corridor in the western extension of the deposit. The hole intersected a new zone located 70 metres to the NW of FW3 Zone returning 4.50 g/t Au over 2.2 metres.

DDH OSK-W-16-727 also tested the Underdog Corridor in the western extension of the deposit. The hole intersected the FW3 Zone returning 9.45 g/t Au over 2.1 metres, located 140 metres in the down-plunge extension of DDH OSK-16-616 (previously reported, 18.9 g/t Au over 2.8 metres). The mineralization is hosted in a strongly silicified porphyry dyke containing 2-20% pyrite stringers and disseminations.

DDH OSK-W-16-706-W3 intersected 7.57 g/t Au over 7.7 metres and expanded the FW1 Zone in the Underdog Corridor by 35 metres along its down-dip extension. The hole also correlates with DDH OSK-16-706 (previously reported, 12.3 g/t Au over 2.3 metres) located 80 metres to the northeast. The gold mineralization is hosted in a fragmental felsic porphyry dyke containing 2-15% pyrite stringers and disseminations with traces of chalcopyrite.

DDH OSK-W-16-708-W2 discovered a new zone in the Underdog Corridor returning 13.8 g/t Au over 6.6 metres. This zone is hosted in a strongly altered volcanic rock unit containing 5-7% pyrite stringers and traces chalcopyrite. The hole also intersected the down-dip extension of the Wolf Zone, returning 4.47 g/t Au over 2.8 metres and expanded a known zone in the Caribou Corridor by another 22 metres down-dip with an interval returning 7.66 g/t Au over 3.0 metres.

DDH OSK-W-16-309-W3 intersected a new zone located 17 metres in the footwall of the Caribou North 1 Zone, returning 11.8 g/t Au over 4.6 metres. This correlates with DDH EAG-13-320-W2, located 62 metres to the SW (previously reported, 4.9 g/t Au over 3.15 metres). The hole intersected additional gold mineralization in the hanging wall of the Caribou North 1 Zone returning 7.63 g/t Au over 2.2 metres and 6.32 g/t Au over 2.1 metres. Both intervals are related to a felsic porphyry dyke.

Qualified Person

The scientific and technical content of this press release has been reviewed, prepared and approved by Mr. Jean-Philippe Desrochers, Ph.D., P.Geo. 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 ("NI 43-101").

Quality Control

True widths of the new exploration intercepts 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. Assays are uncut except where indicated. All NQ core assays reported were obtained by either 1 kg whole rock metallic screen/fire assay or standard 50 gram fire-assaying with AA or gravimetric finish at ALS Laboratories in Val d'Or, Québec or Sudbury, Ontario. The 1 kg 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 analysed for multi-elements, including silver, using an Aqua Regia-ICP-AES method at ALS laboratories. Drill program design, Quality Assurance/Quality Control and interpretation of results is performed by qualified persons employing a QA/QC program consistent with NI 43-101 and industry best practices. Standards and blanks are included with every 20 samples for QA/QC purposes by the Corporation as well as the lab. Approximately 5% of sample pulps are sent to secondary laboratories for check assays.