Osisko Mining Inc. (TSX.OSK)  is pleased to provide new infill drilling results from the ongoing drill definition and expansion program at its 100% owned Windfall Lake gold project located in the Abitibi greenstone belt, Urban Township, Eeyou Istchee James Bay, Québec.  The 800,000 metre drill program commenced in late 2015. The program is currently focussed on infill drilling within the main Windfall gold deposit and the adjacent Lynx deposit (located immediately NE of Windfall), exploration and expansion drilling on the main mineralized zones, and deep exploration in the central areas of the intrusive system. Significant new analytical results from 38 intercepts in 13 drill holes and 4 wedges focused on infill drilling are presented below.

Todays results were not included in the recent Lynx resource update (see Osisko news release dated November 27, 2018).  Highlights from new infill drilling results include: 161 g/t Au over 4.3 metres and 74.4 g/t Au over 2.0 metres in OSK-W-18-1768;  38.9 g/t Au over 13.7 metres and 27.7 g/t Au over 4.4 metres in OSK-W-18-1139-W1;  96.9 g/t Au over 2.6 metres and 32.0 g/t Au over 5.1 metres in OSK-W-18-1770; 16.9 g/t Au over 8.5 metres in OSK-W-18-1760;  53.0 g/t Au over 2.5 metres in OSK-W-18-1756 and 60.3 g/t Au over 2.0 metres in OSK-W-18-1765.  Maps showing hole locations and full analytical results are available at www.osiskomining.com.

Note:       True widths are estimated at 65 – 80% of the reported core length interval.  See “Quality Control and Reporting Protocols” below.

OSK-EAG-13-509 intersected 4.32 g/t Au over 2.4 metres in Zone 27. Mineralization consists of 3% disseminated pyrite and clusters in an andesite with moderate pervasive sericite alteration at the contact with a porphyritic felsic dike.

OSK-W-18-1104-W1 intersected 6.52 g/t Au over 2.0 metres in Lynx. Mineralization consists of up to 1% pyrite in quartz-carbonate crustiform veins and 7% pyrite stringers with pervasive silica flooding. The host is a strong silica and moderate sericite altered fragmental felsic intrusion.

OSK-W-18-1139-W1 intersected five intervals in Underdog: 26.4 g/t Au over 2.3 metres, 38.9 g/t Au over 13.7 metres, 47.8 g/t Au over 2.3 metres, 6.90 g/t Au over 2.0 metres and 27.7 g/t Au over 4.4 metres. The first interval contains up to 15% pyrite stringers within a strongly silicified and sericitized porphyritic felsic dike. The other four intervals all contain local visible gold and up to 7% pyrite within pervasive silica flooding hosted in a moderate to strong sericite and silica altered porphyritic felsic dike.

OSK-W-18-1598-W1 intersected 51.5 g/t Au over 2.0 metres in Lynx. Mineralization consists of local visible gold within pervasive silica flooding and 10% pyrite at the border of a quartz-tourmaline-carbonate crustiform vein. The host is a strong pervasive silica and moderate carbonate altered gabbro with tourmaline veins.

OSK-W-18-1741-W1 intersected 14.0 g/t Au over 2.3 metres in Lynx. Mineralization consists of local visible gold, 2% pyrite with tourmaline infilling fractures within pervasive silica flooding in a moderate to strong silica and sericite altered gabbro.

OSK-W-18-1748 intersected 4.23 g/t Au over 2.0 metres in Lynx. Mineralization consists of traces disseminated and stringer pyrite in a porphyritic felsic dike with tourmaline and moderate chlorite, sericite, silica and carbonate alteration.

OSK-W-18-1756 intersected 53.0 g/t Au over 2.5 metres and 6.72 g/t Au over 2.0 metres in Lynx. The first interval contains local visible gold, up to 8% disseminated pyrite or in stringers with tourmaline and trace chalcopyrite within a weak silica altered rhyolite with local strong carbonate alteration and breccia texture. The second interval contains 3% pyrite with pervasive silica flooding and quartz-tourmaline veinlets within a weak sericite altered rhyolite.

OSK-W-18-1759 intersected 3.80 g/t Au over 2.0 metres in Lynx. Mineralization consists of local visible gold and 7% pyrite with pervasive silica flooding hosted in a moderate sericite and silica altered rhyolite.

OSK-W-18-1760 intersected 3.74 g/t Au over 2.0 metres and 16.9 g/t Au over 8.5 metres in Lynx. The first interval contains 4% pyrite clusters and stringers, mostly as a stockwork within a moderate sericite, weak silica and fuchsite altered gabbro. The second interval contains local visible gold, up to 10% disseminated pyrite and 1% sphalerite within a strong pervasive silica and moderate sericite altered fragmental felsic intrusion.

OSK-W-18-1765 intersected four intervals in Lynx: 3.16 g/t Au over 2.3 metres, 9.84 g/t Au over 2.0 metres, 60.3 g/t Au over 2.0 metres and 7.41 g/t Au over 2.4 metres. The first and second intervals contain 1% pyrite stringers and 1% pyrite fragments in a sericitized porphyritic felsic intrusion. The third interval contains local visible gold and 4% pyrite with pervasive silica flooding within a strong silica, weak fuchsite and sericite altered porphyritic felsic dike. The fourth interval contains up to 5% pyrite stringers and quartz veins with pervasive silica flooding hosted in weak sericite altered rhyolite.

OSK-W-18-1767 intersected 3.67 g/t Au over 2.0 metres in Caribou. Mineralization consists of 3% pyrite stringers and 1% pyrite clusters hosted in a sericite and silica altered porphyritic felsic intrusion.

OSK-W-18-1768 intersected seven intervals in Lynx: 3.65 g/t Au over 2.0 metres, 13.0 g/t Au over 3.4 metres, 4.49 g/t Au over 2.0 metres, 161 g/t Au over 4.3 metres, 22.1 g/t Au over 2.5 metres, 74.4 g/t Au over 2.0 metres and 8.06 g/t Au over 2.3 metres. The first interval contains up to 10% pyrite stringers at the contact between a weak fuchsite and sericite altered gabbro and a rhyolite. The second interval contains local visible gold, 1% disseminated and stringer pyrite and trace sphalerite within pervasive silica flooding located at the contact between a fuchsite altered gabbro and a sericitized rhyolite. The third interval contains trace pyrite-silica flooding and tourmaline veins within a strong sericite, moderate carbonate and silica altered porphyritic felsic intrusion. The fourth interval contains local visible gold with strong pervasive silica flooding and 1% pyrite stringers hosted in a silica altered porphyritic felsic dike. The fifth and sixth intervals contain local visible gold, 2% pyrite stringers and 1% disseminated pyrite within pervasive silica flooding and hosted in sericite, fuchsite and silica altered rhyolite. The last interval contains 1% disseminated pyrite and trace sphalerite with crustiform veins hosted in sericite, silica and fuchsite altered gabbro.

OSK-W-18-1770 intersected five intervals in Lynx: 96.9 g/t Au over 2.6 metres, 11.1 g/t Au over 3.0 metres, 19.0 g/t Au over 2.5 metres, 30.2 g/t Au over 2.2 metres and 32.0 g/t Au over 5.1 metres. The first interval contains traces of pyrite stringers within a sheared and sericite altered andesite. The second interval contains traces of pyrite fragments within a sericite altered gabbro. The third interval contains local visible gold and 5% disseminated pyrite within pervasive silica flooding and hosted in a strong biotite altered rhyolite. The fourth interval contains local visible gold and 3% disseminated pyrite with pervasive silica flooding and fuchsite alteration hosted in a strong silica, biotite and sericite altered rhyolite. The last interval contains local visible gold and up to 7% disseminated and stringer pyrite and with pervasive silica flooding hosted in a silica, fuchsite and biotite altered rhyolite.

OSK-W-18-1771 intersected 6.83 g/t Au over 2.2 metres in Caribou. Mineralization consists of 5% pyrite clusters and 5% disseminated pyrite within a strong fault zone hosted in a silicified and sericitized rhyolite.

OSK-W-18-1772 intersected three intervals in Lynx: 19.1 g/t Au over 2.1 metres, 31.3 g/t Au over 2.1 metres and 11.9 g/t Au over 2.0 metres. The first interval contains 1% pyrite stringers hosted in moderate silica and sericite altered rhyolite. The second interval contains 1% disseminated and stringer pyrite and up to 2% sphalerite with pervasive silica flooding hosted at a sericite, silica and fuchsite altered contact between a felsic intrusion and a rhyolite. The third interval contains 1% disseminated and clustered pyrite and ptygmatic tourmaline veins within a moderate sericite, carbonates and fuchsite altered rhyolite.

WST-18-0017 intersected 12.8 g/t Au over 2.4 metres in Zone 27. Mineralization consists of 1% disseminated pyrite and stringers within a moderate sericite and silica altered andesite.

WST-18-0024 intersected 26.5 g/t Au over 2.4 metres in Mallard. Mineralization consists of disseminated pyrite with a crustiform vein hosted in weak sericite altered andesite.

Qualified Person

The scientific and technical content of this news release has been reviewed, prepared and approved by Mr. Louis Grenier, M.Sc.A., P.Geo. (OGQ 800), Project Manager of Osisko’s 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 width determination is estimated at 65-80% of the reported core length interval for the zone. Assays are uncut except where indicated. Intercepts occur within geological confines of major zones but have not been correlated to individual vein domains at this time. Reported intervals include minimum weighted averages of 3.0 g/t Au diluted over core lengths of at least 2.0 metres. All NQ core assays reported were obtained by either 1-kilogram screen fire assay or standard 50-gram fire-assaying-AA finish or gravimetric finish at (i) ALS Laboratories in Val d’Or, Québec, Thunder Bay, Ontario, Sudbury, Ontario or Vancouver, British Colombia, or (ii) Bureau Veritas in Timmins, Ontario. The 1-kilogram screen assay method is selected by the geologist when samples contain coarse gold or present a higher percentage of pyrite than surrounding intervals. Selected samples are also analyzed 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 assay.

About the Windfall Lake Gold Deposit

The Windfall Lake gold deposit is located between Val-d’Or and Chibougamau in the Abitibi region of Québec, Canada. The mineral resource defined by Osisko, as disclosed in the Windfall Lake Technical Report (as defined below) and November 27, 2018 Lynx resource update, comprises 2,874,000 tonnes at 8.17 g/t Au (754,000 ounces) in the indicated mineral resource category and 10,352,000 tonnes at 7.11 g/t Au (2,366,000 ounces) in the inferred mineral resource category. For details regarding the key assumptions, parameters and methods used to estimate the mineral resources presented in respect of the Windfall Lake gold project, please see the technical report entitled “Technical Report and Mineral Resource Estimate for the Windfall Lake Project, Windfall Lake and Urban-Barry Properties” and dated June 12, 2018 (effective date of May 14, 2018), which has been prepared by InnovExplo Inc. from Val-d’Or, Québec (the “Windfall Lake Technical Report”) and the press release “Osisko Releases Mineral Resource Update for Lynx” dated November 27, 2018, which has been prepared by Osisko and reviewed and approved by Micon International, Ltd. from Toronto, Ontario. The Windfall Lake Technical Report and press release are available on Osisko’s website at www.osiskomining.com and on SEDAR under Osisko’s issuer profile at www.sedar.com. The Windfall Lake gold deposit is currently one of the highest grade resource-stage gold projects in Canada. Mineralization occurs in four principal zones: Lynx, Zone 27, Caribou and Underdog. All zones comprise sub-vertical lenses following intrusive porphyry contacts plunging to the northeast. The deposit is well defined from surface to a depth of 900 metres and remains open along strike and at depth. Mineralization has been identified 30 metres from surface in some areas and as deep as 2,000 metres in others, with significant potential to extend mineralization 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% interest in the high-grade Windfall Lake gold deposit located between Val-d’Or and Chibougamau in Québec and holds a 100% undivided interest in a large area of claims in the surrounding the Urban Barry area and nearby Quevillon area (over 3,300 square kilometres), a 100% interest in the Marban project located in the heart of Québec’s prolific Abitibi gold mining district, and properties in the Larder Lake Mining Division in northeast Ontario, including the Garrison property. The Corporation also holds interests and options in a number of additional properties in northern Québec and Ontario.