OSISKO INFILL DRILLING INTERSECTS HIGH-GRADE AT LYNX

Multiple High-Grade Intercepts Including 80.7 g/t Au Over 5.8 Metres

(Toronto, September 5, 2019) Osisko Mining Inc. (OSK:TSX. “Osisko” or the “Corporation”) is pleased to provide new infill drilling results from the ongoing definition and expansion program at its 100% owned Windfall gold project located in the Abitibi greenstone belt, Urban Township, Eeyou Istchee James Bay, Québec. The program is currently focused 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 72 intercepts in 38 drill holes and 16 wedges from surface focused on Lynx and Main Zone infill drilling are presented below. Additionally, 66 intercepts in 29 underground drill holes focused on multiple spacing infill drilling, including the pending Lynx bulk sample area, are included in a second table below.

Osisko President and Chief Executive Officer John Burzynski commented: “Infill drilling has been defining good continuity within the known zones and is showing some very strong grades particularly in Lynx.  The recently announced addition of 200,000 metres of drilling should also allow us to add significant areas from the two new discoveries (the Lynx Extension and Triple Lynx) to the resource work by the end of the year.”

Highlights from new infill drilling results include: 80.7 g/t Au over 5.8 metres in OSK-W-19-1958-W2; 104 g/t Au over 3.6 metres in OSK-W-19-1539-W1; 151 g/t Au over 2.1 metres in WST-19-0168; 89.2 g/t Au over 2.9 metres in WST-19-167; 114 g/t Au over 2.1 metres in WST-19-0143; 52.3 g/t Au over 4.2 metres in OSK-W-19-2012; 81.0 g/t Au over 2.7 metres in WST-19-0142A; 53.1 g/t Au over 3.3 metres in OSK-W-19-1949-W1; 50.9 g/t Au over 2.5 metres in WST-19-0172; 14.5 g/t Au over 7.3 metres in WST-19-0132 and 50.0 g/t Au over 2.0 metres in OSK-W-19-1412-W3. Maps showing hole locations and full analytical results are available at www.osiskomining.com.

Surface Drilling

Underground drilling

Notes: True widths are estimated at 55 – 80% of the reported core length interval. See “Quality Control and Reporting Protocols” below.

Surface Drilling

Underground drilling

OSK-W-17-961 intersected 37.7 g/t Au over 2.3 metres in Lynx. Mineralization consists of up to 5% pyrite in stringers, clusters and disseminated, and up to 2% quartz-tourmaline veins at the contact between a moderate fuchsite altered gabbro and a strong sericite altered rhyolite.

OSK-W-18-1746 intersected 25.3 g/t Au over 2.1 metres in Lynx. Mineralization consists of up to 4% pyrite stringers and up to 10% quartz-tourmaline veins within a moderate sericite altered felsic porphyritic intrusion.

OSK-W-19-1181-W7 intersected 7.93 g/t Au over 2.4 metres in Lynx. Mineralization consists of up to 7% disseminated and stringer pyrite and trace chalcopyrite associated with quartz-tourmaline veins within moderate sericite, silica and fuchsite altered gabbro.

OSK-W-19-1412-W3 intersected 50.0 g/t Au over 2.0 metres in Lynx. Mineralization consists of 5% pyrite stringers and 1% ptygmatic tourmaline veins within a moderate sericite altered felsic intrusion.

OSK-W-19-1419-W1 intersected 9.13 g/t Au over 3.9 metres in Lynx. Mineralization consists of 5% disseminated and stringer pyrite hosted in a moderate silica altered rhyolite.

OSK-W-19-1539-W1 intersected 104 g/t Au over 3.6 metres in Lynx. Mineralization consists of local visible gold, 10% disseminated pyrite with strong pervasive silica alteration and quartz-tourmaline veins hosted in a strong silica, sericite and fuchsite altered rhyolite.

OSK-W-19-1746-W1 intersected 4.38 g/t Au over 3.1 metres in Lynx. Mineralization consists of 10% quartz-tourmaline veins and disseminated pyrite within a strong sericite altered andesite.

OSK-W-19-1857-W1 intersected 5.37 g/t Au over 2.2 metres in Lynx. Mineralization consists of up to 2% pyrite clusters within a quartz vein and quartz-tourmaline veins hosted in a moderate fuchsite, weak silica and sericite altered gabbro.

OSK-W-19-1857-W3 intersected two intervals in Lynx: 38.8 g/t Au over 2.0 metres and 6.43 g/t Au over 2.3 metres. The first interval contains 4% pyrite stringers and clusters and quartz-tourmaline veins hosted in a strong silica altered rhyolite. The second interval contains local visible gold associated with a smoky quartz vein and 4% pyrite clusters in a moderate sericite altered gabbro.

OSK-W-19-1889 intersected 7.82 g/t Au over 2.3 metres in Caribou. Mineralization consists of 2% disseminate pyrite and crustiform quartz-tourmaline veins within a weak sericite altered gabbro.

OSK-W-19-1891 intersected 4.46 g/t Au over 2.1 metres in Lynx. Mineralization consists of 5% disseminated pyrite and quartz veins hosted in a moderate sericite, chlorite gabbro.

OSK-W-19-1891-W1 intersected 7.18 g/t Au over 3.0 metres in Lynx. Mineralization consists of 2% pyrite stringers and disseminated pyrite within a quartz vein hosted in a moderate sericite and weak silica altered fragmental felsic intrusion.

OSK-W-19-1891-W4 intersected 14.0 g/t Au over 2.5 metres in Lynx. Mineralization consists of 7% pyrite stringers and clusters associated with pervasive silica flooding hosted in a moderate sericite and fuchsite altered gabbro.

OSK-W-19-1903 intersected 6.18 g/t Au over 2.8 metres in Caribou. Mineralization consists of 1% disseminated pyrite hosted in a weak sericite and silica altered contact between a rhyolite and a porphyritic felsic intrusion.

OSK-W-19-1904 intersected two intervals: 4.14 g/t Au over 2.1 metres in Caribou and 3.93 g/t Au over 3.0 metres in Zone 27. The first interval contains 25% pyrite stringers and clusters within a weak sericite and silica altered rhyolite. The second interval contains 1% disseminate and stringer pyrite within a weak sericite and silica altered porphyritic felsic intrusion.

OSK-W-19-1917 intersected 3.62 g/t Au over 2.0 metres in Caribou. Mineralization consists of up to 30% semi-massive pyrite within a strong sericite and carbonate altered andesite.

OSK-W-19-1921-W2 intersected 5.88 g/t Au over 2.9 metres in Lynx. Mineralization consists of up to 10% disseminated pyrite in quartz-tourmaline veins, tourmaline stringers, and pyrite clusters hosted in a moderate silica altered rhyolite.

OSK-W-19-1928 intersected 37.8 g/t Au over 2.1 metres in Lynx. Mineralization consists of 1% pyrite stringers hosted in a moderate fuchsite and chlorite altered fragmental felsic intrusion.

OSK-W-19-1942 intersected 6.66 g/t Au over 2.0 metres in Lynx. Mineralization consists of trace disseminated and stringer pyrite within a moderate sericite and weak silica altered rhyolite.

OSK-W-19-1942-W2 intersected four intervals in Lynx: 9.48 g/t Au over 2.0 metres, 9.90 g/t Au over 3.0 metres, 15.2 g/t Au over 2.2 metres and 6.89 g/t Au over 4.8 metres. The first interval contains 3% pyrite clusters and stringers at the contact between a moderate sericite altered felsic porphyritic intrusion and a moderate chlorite and fuchsite altered gabbro. The second interval contains 15% pyrite, 1% galena, 1% chalcopyrite and trace sphalerite within a weak fuchsite, carbonate and sericite altered rhyolite. The third interval is composed of local visible gold, up to 20% pyrite, trace galena, molybdenite, chalcopyrite and sphalerite hosted in weak sericite altered rhyolite. The last interval contains up to 5% disseminated pyrite and stringers, and smoky quartz veins within a moderate sericite and silica altered gabbro.

OSK-W-19-1943 intersected 5.46 g/t Au over 2.0 metres in Windfall North. Mineralization consists of up to 10% disseminated pyrite and clusters, trace chalcopyrite and crustiform quartz-carbonate veins within a moderate sericite altered porphyritic felsic intrusion.

OSK-W-19-1949-W1 intersected two intervals in Lynx: 53.1 g/t Au over 3.3 metres and 20.2 g/t Au over 2.0 metres. The first interval contains local visible gold and native silver within pervasive silica flooding, 5% pyrite stringers and 2% pyrite clusters hosted in a strong sericite and silica altered rhyolite. The second interval is composed of 1% disseminated and stringer pyrite within a weak sericite altered rhyolite.

OSK-W-19-1949-W2 intersected 7.88 g/t Au over 3.1 metres in Lynx. Mineralization consists of trace pyrite clusters hosted in a strong sericite and moderate silica altered rhyolite.

OSK-W-19-1950 intersected 38.9 g/t Au over 2.3 metres in Windfall North. Mineralization consists of local visible gold, 3% disseminated pyrite and 5% pyrites clusters with quartz-carbonate veins hosted in a moderate silica altered felsic intrusion.

OSK-W-19-1954 intersected 27.8 g/t Au over 2.8 metres in Windfall North. Mineralization consists of up to 10% fine disseminated pyrite and quartz-carbonate veins within a strong sericite altered rhyolite.

OSK-W-19-1958 intersected two intervals in Lynx: 12.9 g/t Au over 2.3 metres and 7.94 g/t Au over 7.0 metres. Mineralization in both intervals consists of local visible gold, 3% pyrite stringers with pervasive silica flooding and quartz-tourmaline veins hosted in moderate sericite fragmental felsic intrusion.

OSK-W-19-1958-W1 intersected four intervals in Lynx: 8.50 g/t Au over 2.4 metres, 3.51 g/t Au over 2.0 metres, 8.31 g/t Au over 2.5 metres and 5.14 g/t Au over 2.2 metres. The first interval contains up to 8% disseminated pyrite, stringers and clusters hosted at the contact between a fuchsite altered gabbro and a felsic intrusion. The second interval is composed of trace pyrite stringers within a strong chlorite altered rhyolite. The third interval contains up to 2% pyrite stringers within a weak sericite altered rhyolite. The last interval contains up to 7% pyrite stringers hosted in a strong carbonate and weak sericite altered felsic porphyritic intrusion.

OSK-W-19-1958-W2 intersected 80.7 g/t Au over 5.8 metres in Lynx. Mineralization consists of local visible gold in fracture filling, 8% pyrite clusters and stringers, trace chalcopyrite and sphalerite, quartz-tourmaline at the contact between a strong silica and fuchsite altered gabbro with a strong sericite altered rhyolite.

OSK-W-19-1966 intersected 4.69 g/t Au over 2.0 metres in Windfall North. Mineralization consists of 1% pyrite clusters within a moderate fuchsite altered and bleached rhyolite.

OSK-W-19-1969 intersected 3.09 g/t Au over 2.0 metres in Lynx. Mineralization consists of local visible gold associated with pervasive silica flooding and up to 5% fine disseminated pyrite hosted in a moderate sericite altered gabbro.

OSK-W-19-1971 intersected 3.28 g/t Au over 2.4 metres in Windfall North. Mineralization consists of 7% pyrite stringers and quartz-tourmaline veins hosted in a moderate silica, carbonate and sericite altered gabbro.

OSK-W-19-1978 intersected 12.1 g/t Au over 2.0 metres in Windfall North. Mineralization consists of 5% fine disseminated pyrite and stringers, trace chalcopyrite and 3% quartz-carbonate veins hosted in a moderate chlorite altered and bleached andesite.

OSK-W-19-1982 intersected 10.6 g/t Au over 3.2 metres in Bobcat. Mineralization consists of local visible gold, up to 6% pyrite with quartz-carbonates veins and ptygmatic tourmaline veins hosted in a weak sericite and silica altered porphyritic felsic intrusion.

OSK-W-19-1991 intersected 5.27 g/t Au over 2.2 metres in Lynx. Mineralization consists of 3% pyrite and trace sphalerite associated with pervasive silica flooding, smoky quartz veins and pyrite-tourmaline stringers hosted in a moderate sericite and weak silica altered felsic porphyritic intrusion.

OSK-W-19-1999 intersected 29.0 g/t Au over 2.2 metres in Bobcat. Mineralization consists of up to 15% semi-massive pyrite and ptygmatic tourmaline veins within a moderate silica altered rhyolite.

OSK-W-19-2003 intersected 3.06 g/t Au over 4.4 metres in Bobcat. Mineralization consists of 6% disseminated and stringer pyrite associated with quartz-tourmaline veins hosted in a moderate fuchsite altered gabbro.

OSK-W-19-2004 intersected 5.31 g/t Au over 3.3 metres in Bobcat. Mineralization consists of 2% pyrite stringers and quartz-carbonate veins hosted in a moderate sericite and weak fuchsite altered gabbro.

OSK-W-19-2009 intersected two intervals in Bobcat: 3.87 g/t Au over 2.2 metres and 4.97 g/t Au over 4.1 metres. Both intervals are composed of 3% pyrite stringers and quartz-tourmaline veins hosted in a moderate sericite and fuchsite altered gabbro.

OSK-W-19-2011 intersected 22.6 g/t Au over 2.2 metres in Lynx. Mineralization consists of local visible gold and 2% fine disseminated pyrite hosted in a strong fuchsite altered felsic intrusion.

OSK-W-19-2012 intersected 52.3 g/t Au over 4.2 metres in Lynx. Mineralization consists of local visible gold with pyrite-silica flooding and 1% pyrite clusters hosted in a moderate silica and sericite altered felsic intrusion.

OSK-W-19-2013 intersected 15.5 g/t Au over 2.6 metres in F11. Mineralization consists of local visible gold, up to 2% disseminated pyrite and quartz-carbonate veins hosted in a weak carbonate altered andesite.

OSK-W-19-2015 intersected two intervals in Lynx: 32.9 g/t Au over 2.0 metres and 3.38 g/t Au over 2.1 metres. The first interval contains up to 3% pyrite, 1% chalcopyrite and ptygmatic tourmaline veins within a strong silica, chlorite, and fuchsite altered andesite. The second interval is composed of 1% pyrite stringers hosted in a moderate sericite and chlorite altered andesite.

OSK-W-19-2020 intersected four intervals in Bobcat: 9.10 g/t Au over 2.0 metres, 7.22 g/t Au over 2.0 metres, 5.61 g/t Au over 2.0 metres and 3.14 g/t Au over 2.0 metres. The first interval contains trace disseminated pyrite within a moderate sericite altered porphyritic felsic intrusion. The second interval contains up to 10% pyrite stringers within a moderate sericite and weak silica altered porphyritic felsic intrusion. The third interval is composed of 10% pyrite stringers in stockwork and pyrite-silica flooding within a string silica altered porphyritic felsic intrusion. The last interval contains 1% pyrite stringers at the contact between a gabbro and a felsic intrusion.

OSK-W-19-2023 intersected 37.2 g/t Au over 2.0 metres in Bobcat. Mineralization consists of up to 3% pyrite stringers hosted at the contact between a weak sericite altered felsic intrusion and a chloritized gabbro.

OSK-W-19-2025 intersected three intervals in Bobcat: 7.24 g/t Au over 2.5 metres, 6.88 g/t Au over 2.5 metres and 3.71 g/t Au over 2.0 metres. The first interval contains 10% pyrite stringers and clusters hosted in a moderate silica altered rhyolite. The second interval contains 10% pyrite clusters and stringers within a weak sericite altered porphyritic felsic intrusion. The last interval consists of up to 3% pyrite clusters and quartz-tourmaline veins within a weak sericite and a strong silica altered porphyritic felsic intrusion.

OSK-W-19-2032 intersected 3.25 g/t Au over 2.1 metres in Underdog. Mineralization consists of up to 10% pyrite stringers and clusters and quartz-tourmaline veins hosted in a weak sericite altered porphyritic felsic intrusion.

OSK-W-19-2033 intersected 13.5 g/t Au over 2.5 metres in Bobcat. Mineralization consists of 3% pyrite stringers and clusters with quartz-tourmaline veins hosted in a weak sericite altered fragmental felsic rhyolite.

OSK-W-19-2035 intersected 4.55 g/t Au over 2.3 metres in Lynx. Mineralization consists of 3% disseminated pyrite and quartz-tourmaline veins hosted in a weak sericite and silica altered fragmental felsic intrusion.

OSK-W-19-2036 intersected 16.6 g/t Au over 2.1 metres in Bobcat. Mineralization consists of local visible gold and native silver, 5% pyrite stringers, 2% chalcopyrite, and quartz-tourmaline crustiform veins hosted in a moderate sericite and weak fuchsite altered gabbro.

OSK-W-19-2037 intersected 14.9 g/t Au over 2.0 metres in F11. Mineralization consists of 5% fine disseminated pyrite within a moderated chlorite altered andesite.

OSK-W-19-2038 intersected two intervals in Bobcat: 18.2 g/t Au over 2.4 metres and 22.9 g/t Au 2.0 metres. The first interval contains 3% disseminated pyrite and stringers with quartz-carbonate veins hosted in a weak sericite and fuchsite altered gabbro.

OSK-W-19-2046 intersected 3.84 g/t Au over 2.1 metres in F17. Mineralization consists of 2% fine disseminated and stringer pyrite with quartz-tourmaline veins hosted in a weak sericite and chlorite altered andesite at the contact of a small hematized monzonite Red Dog-type intrusion.

OSK-W-19-2055 intersected 7.03 g/t Au over 2.1 metres in F51. Mineralization consists of up to 6% disseminated pyrite, 2% pyrite clusters and pervasive pyrite-silica flooding hosted in a moderate silica altered porphyritic felsic intrusion.

OSK-W-19-934-W4 intersected 4.60 g/t Au over 2.6 metres in Lynx. Mineralization consists of 2% disseminated and stringer pyrite within a weak sericite, chlorite and fuchsite altered rhyolite.

WST-19-0072 intersected 5.07 g/t Au over 2.0 metres in Zone 27. Mineralization consists of up to 10% pyrite stringers hosted in a weak sericite altered rhyolite. WST-19-0072 was drilled from underground drill station BF-160-150-S located 160 metres below surface from section 2400E.

WST-19-093 intersected 24.6 g/t Au over 2.1 metres in Lynx. Mineralization consists of 1% pyrite stringers with pyrite-silica flooding hosted in a strong silica, moderate sericite and weak fuchsite altered fragmental felsic intrusion. WST-19-093 was drilled from underground drill station RA-180-190-E located 180 metres below surface from section 3450E.

WST-19-0132 intersected 14.5 g/t Au over 7.3 metres in Lynx. Mineralization consists of local visible gold, 3% pyrite clusters associated with pyrite-silica flooding hosted in a strong silica and moderate fuchsite altered fragmental felsic intrusion. WST-19-0132 was drilled from underground drill station RE-195-265-O located 195 metres below surface from section 3475E.

WST-19-0133 intersected 26.2 g/t Au over 3.0 metres in Lynx. Mineralization consists of local visible gold, up to 10% pyrite clusters and stringers within a strong silica and fuchsite altered felsic intrusion. WST-19-0133 was drilled from underground drill station RE-195-265-O located 195 metres below surface from section 3475E.

WST-19-0134 intersected 16.6 g/t Au over 2.0 metres in Lynx. Mineralization consists of local visible gold, 2% pyrite clusters and stringers, trace sphalerite associated with pyrite-silica flooding, hosted in a moderate sericite altered felsic intrusion. WST-19-0134 was drilled from underground drill station RE-195-265-O located 195 metres below surface from section 3475E.

WST-19-0138 intersected two interval in Lynx: 13.5 g/t Au over 2.0 metres and 45.9 g/t Au over 2.0 metres. The first interval contains 2% disseminated pyrite and quartz veins within a moderate sericite and silica altered felsic intrusion. The second interval contains local visible gold, 2% disseminated pyrite and trace sphalerite associate with pyrite-silica flooding and hosted in a strong silica, sericite and fuchsite altered fragmental felsic intrusion. WST-19-0138 was drilled from underground drill station AN-195-265-S located 195 metres below surface from section 3500E.

WST-19-0142A intersected three intervals in Lynx: 11.5 g/t Au over 2.4 metres, 9.86 g/t Au over 3.5 metres and 81.0 g/t Au over 2.7 metres. The first interval contains 6% disseminated pyrite and quartz-tourmaline veins within a strong pervasive silica altered rhyolite. The second interval is composed of up to 6% pyrite stringers within a strong silica altered rhyolite. The third interval contains local visible gold, 6% disseminated and stringer pyrite within a strong silica altered rhyolite. WST-19-0142A was drilled from underground drill station AN-195-265-S located 195 metres below surface from section 3500E.

WST-19-0143 intersected 114 g/t Au over 2.1 metres in Lynx. Mineralization contains local visible gold associated with pyrite-silica flooding, up to 3% pyrite stringers and trace sphalerite within a strong silica, sericite and fuchsite altered rhyolite. WST-19-0143 was drilled from underground drill station AN-195-265-S located 195 metres below surface from section 3500E.

WST-19-0144 intersected two intervals in Lynx: 5.61 g/t Au over 2.9 metres and 9.42 g/t Au over 2.2 metres. The first interval contains local visible gold and 15% pyrite stringers within a strong silica altered fragmental felsic intrusion. The second interval contains local visible gold, 5% fine disseminated pyrite hosted in a strong pervasive silica altered fragmental intrusion. WST-19-0144 was drilled from underground drill station AN-195-265-S located 195 metres below surface from section 3500E.

WST-19-0151 intersected two intervals in Lynx: 30.4 g/t Au over 2.0 metres and 32.0 g/t Au over 2.1 metres. The first interval contains 20% pyrite and 1% sphalerite associated with pyrite-silica flooding, hosted in a moderate silica altered fragmental felsic intrusion. The second interval contains local visible gold, 5% disseminated pyrite and quartz veins at the contact between a moderate silica altered felsic intrusion with a strong silica altered rhyolite. WST-19-0151 was drilled from underground drill station BM-200-285-S located 200 metres below surface from section 3525E.

WST-19-0154 intersected four intervals in Lynx: 8.65 g/t Au over 2.0 metres, 4.93 g/t Au over 2.3 metres, 7.04 g/t Au over 2.1 metres and 12.8 g/t Au over 2.8 metres. The first interval contains 2% pyrite stringers at the contact between a moderate sericite, weak silica and fuchsite altered gabbro with a fragmental felsic intrusion. The second interval is composed of 10% pyrite-silica flooding within a moderate silica and weak sericite altered fragmental felsic intrusion. The third interval contains up to 10% pyrite-silica flooding and quartz veins hosted at the contact between a fragmental felsic intrusion and a porphyritic felsic intrusion. The last interval contains local visible gold and 10% pyrite-silica flooding within a porphyritic felsic intrusion. WST-19-0154 was drilled from underground drill station BM-200-285-S located 200 metres below surface from section 3525E.

WST-19-0155 intersected three intervals in Lynx: 4.67 g/t Au over 3.3 metres, 5.79 g/t Au over 2.5 metres and 3.04 g/t Au over 2.0 metres. The first interval contains 3% disseminated pyrite in a weak sericite altered rhyolite. The second interval is composed of 3% pyrite stringers in a weak sericite altered rhyolite. The third interval is composed of 1% pyrite stringers and up to 15% quartz-tourmaline veins within a moderate chlorite and weak sericite altered rhyolite. WST-19-0155 was drilled from underground drill station RE-195-265-O located 185 metres below surface from section 3500E.

WST-19-0157 intersected 9.84 g/t Au over 2.6 metres in Lynx. Mineralization consists of local visible gold, 10% disseminated pyrite and trace sphalerite within a strong silica altered rhyolite. WST-19-0157 was drilled from underground drill station BM-200-285-S located 200 metres below surface from section 3525E.

WST-19-0159 intersected two intervals in Zone 27: 9.86 g/t Au over 2.9 metres and 3.93 g/t Au over 2.0 metres. The first interval contains fine disseminated pyrite and stringers within a moderately bleached felsic intrusion. The second interval contains 5% disseminated and stringer pyrite within a moderate sericite altered andesite. WST-19-0159 was drilled from underground drill station AN-195-225-E located 195 metres below surface from section 2400E.

WST-19-0160A intersected 7.15 g/t Au over 2.4 metres in Zone 27. Mineralization consists of up to 5% disseminated pyrite within a moderate sericite and weak silica altered andesite. WST-19-0160A was drilled from underground drill station AN-195-225-E located 195 metres below surface from section 2400E.

WST-19-0161A intersected 5.70 g/t Au over 3.0 metres in Caribou. Mineralization consists of 3% disseminated pyrite and quartz veins within a moderate sericite altered andesite. WST-19-0161A was drilled from underground drill station AN-195-225-E located 195 metres below surface from section 2400E.

WST-19-0164 intersected five intervals in Lynx: 6.85 g/t Au over 2.0 metres, 3.54 g/t Au over 2.0 metres, 14.0 g/t Au over 2.0 metres, 8.98 g/t Au over 2.4 metres and 30.3 g/t Au over 2.0 metres. The first interval contains up to 3% disseminated pyrite and ptygmatic quartz-tourmaline veins within a moderate sericite altered felsic intrusion. The second and third intervals are composed of 5% fine disseminated pyrite and stringers associated with pyrite-silica flooding and hosted in a moderate sericite altered rhyolite. The fourth interval contains fine trace pyrite and ptygmatic tourmaline veins within a moderate sericite and chlorite altered rhyolite. The last interval consists of local visible gold and fine pyrite in pyrite-silica flooding hosted in a strong silica and moderate fuchsite altered rhyolite. WST-19-0168 was drilled from underground drill station BM-200-285-S located 200 metres below surface from section 3525E.

WST-19-0165A intersected three intervals in Lynx: 9.81 g/t Au over 2.0 metres, 10.6 g/t Au over 2.0 metres, and 4.56 g/t Au over 2.0 metres. The first two intervals contain 1% pyrite clusters within a moderate sericite and weak silica altered fragmental intrusion. The last interval is composed of 3% fine disseminated pyrite associated with pyrite-silica flooding hosted in a moderate sericite altered felsic intrusion. WST-19-0165A was drilled from underground drill station BM-200-285-S located 200 metres below surface from section 3525E.

WST-19-0167 intersected four intervals in Lynx: 15.1 g/t Au over 2.0 metres, 8.55 g/t Au over 2.0 metres, 20.7 g/t Au over 4.3 metres and 89.2 g/t Au over 2.9 metres. The first interval contains up to 3% disseminated pyrite and smoky quartz veins within a strong silica altered fragmental felsic intrusion. The second interval contains 1% pyrite clusters within a moderate sericite altered fragmental felsic intrusion. The third interval is composed of local visible gold, up to 5% disseminated, clustered and stringer pyrite associated with pervasive pyrite-silica flooding hosted in moderate sericite and silica altered rhyolite. The last interval contains local visible gold, 10% disseminated pyrite and quartz-carbonate veins within a moderate sericite and silica altered felsic intrusion. WST-19-0167 was drilled from underground drill station BM-200-285-S located 200 metres below surface from section 3525E.

WST-190168 intersected four intervals in Lynx: 6.94 g/t Au over 2.2 metres, 14.8 g/t Au over 2.0 metres, 5.66 g/t Au over 2.0 metres and 151 g/t Au over 2.1 metres. The first interval contains 3% disseminated pyrite and ptygmatic tourmaline veins within a moderate sericite altered felsic intrusion. The second interval contains 5% disseminated pyrite and stringers within a moderate sericite altered rhyolite. The third interval contains trace disseminated pyrite and ptygmatic tourmaline vein within a moderate sericite, carbonate and silica altered rhyolite. The last interval is composed of local visible gold and native silver associated with pervasive pyrite-silica flooding and quartz veins hosted in a moderate sericite, silica and fuchsite altered porphyritic felsic intrusion. WST-19-0168 was drilled from underground drill station BM-200-285-S located 200 metres below surface from section 3525E.

WST-19-0169 intersected three intervals in Lynx: 6.30 g/t Au over 2.1 metres, 12.0 g/t Au over 2.0 metres and 16.7 g/t Au over 2.8 metres. The first interval contains 5% disseminated pyrite within a felsic fragmental intrusion. The second interval is composed of local visible gold associated with pervasive pyrite-silica flooding and 10% pyrite stringers within a moderate sericite altered felsic intrusion. The last interval contains local visible gold, up 15% disseminated and stringer pyrite, and quartz crustiform veins within a medium silica and weak sericite altered rhyolite. WST-19-0169 was drilled from underground drill station BM-200-285-S located 200 metres below surface from section 3525E.

WST-19-0170 intersected four intervals in Lynx: 2.23 g/t Au over 3.0 metres, 9.74 g/t Au over 2.6 metres, 5.46 g/t Au over 2.0 metres and 5.50 g/t Au over 2.8 metres. The first interval contains 3% pyrite in pyrite-silica flooding within a moderate silica altered felsic intrusion. The second interval contains 10% disseminated pyrite and ptygmatic tourmaline veins in a moderate silica altered felsic intrusion. The third interval is composed of 2% pyrite and ptygmatic tourmaline veins within a moderate silica altered felsic intrusion. The last interval contains 2% pyrite stringers in stockwork within a moderate silica altered andesite. WST-19-0170 was drilled from underground drill station BM-200-285-S located 200 metres below surface from section 3525E.

WST-19-0172 intersected four intervals in Lynx: 50.9 g/t Au over 2.5 metres, 32.4 g/t Au over 2.3 metres, 22.7 g/t Au over 2.7 metres and 4.09 g/t Au over 2.1 metres. The first interval contains local visible gold, 15% disseminated pyrite and 2% sphalerite within a strong silica altered rhyolite. The second interval is composed of local visible gold, 2% pyrite stringers associated with pyrite-silica flooding and hosted in a moderate silica altered porphyritic felsic intrusion. The third interval contains local visible gold, 10% disseminated and quartz veins within a strong silica and fuchsite altered porphyritic felsic intrusion. The last interval contains 2% pyrite stringers and quartz-tourmaline vein hosted in a moderate silica altered rhyolite. WST-19-0172 was drilled from underground drill station BM-200-285-S located 200 metres below surface from section 3525E.

WST-19-0177 intersected three intervals in Lynx: 9.13 g/t Au over 2.1 metres, 6.31 g/t Au over 3.7 metres and 4.67 g/t Au over 4.0 metres. The first interval contains 2% pyrite clusters and ptygmatic quartz-tourmaline veins within a moderate silica and weak sericite altered rhyolite. The second interval contains 1% pyrite clusters and stringers within a moderate silica altered rhyolite. The last interval is composed of trace pyrite clusters and stringers within a weak sericite and silica altered rhyolite. WST-19-0177 was drilled from underground drill station BM-200-285-S located 200 metres below surface from section 3525E.

WST-19-0178 intersected 9.82 g/t Au over 2.2 metres in Lynx. Mineralization consists of 5% pyrite clusters and stringers at the contact between a strong sericite altered gabbro and a moderate sericite altered rhyolite. WST-19-0178 was drilled from underground drill station BM-200-285-S located 200 metres below surface from section 3525E.

WST-19-0179 intersected four intervals in Lynx: 36.2 g/t Au over 2.0 metres, 3.01 g/t Au over 2.0 metres, 3.43 g/t Au over 2.0 metres and 10.9 g/t Au over 2.6 metres. The first interval contains local visible gold, 2% pyrite stringers and 10% quartz-carbonate-tourmaline veins within a weak sericite and moderate silica altered rhyolite. The second and third intervals contain 1% pyrite clusters and stringers within a moderate sericite altered rhyolite. The last interval is composed of local visible gold, 1% disseminated pyrite and clusters with quartz-tourmaline veins hosted in a weak sericite and silica altered rhyolite. WST-19-0179 was drilled from underground drill station BM-220-280-O located 220 metres below surface from section 3500E.

WST-19-0180 intersected 3.62 g/t Au over 2.2 metres in Lynx. Mineralization consists of 2% pyrite-tourmaline stringers within a weak sericite altered rhyolite. WST-19-0180 was drilled from underground drill station BM-220-280-O located 220 metres below surface from section 3500E.

WST-19-0181 intersected two intervals in Lynx: 3.91 g/t Au over 2.1 metres and 14.1 g/t Au over 2.2 metres. The first interval is composed of local visible gold, up to 3% pyrite clusters associated with pyrite-silica flooding hosted in a moderate sericite and strong silica altered rhyolite. The second interval contains local visible gold, up to 7% disseminated pyrite, trace chalcopyrite and quartz-carbonate veins within a moderate fuchsite and silica altered gabbro. WST-19-0181 was drilled from underground drill station BM-220-280-O located 220 metres below surface from section 3500E.

WST-19-0182 intersected 33.3 g/t Au over 2.0 metres in Lynx. Mineralization consists of up to 3% pyrite clusters and stringers within a weak silica and moderate sericite altered felsic intrusion. WST-19-0182 was drilled from underground drill station BM-220-280-O located 220 metres below surface from section 3500E.

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 (“NI 43-101”).

Quality Control and Reporting Protocols

True width determination is estimated at 55-80% 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 (“QA/QC”) 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 Quévillon area (over 2,700 square kilometres).

Cautionary Note Regarding Forward-Looking Information

This news release contains “forward-looking information” within the meaning of the applicable Canadian securities legislation that is based on expectations, estimates, projections and interpretations as at the date of this news release. The information in this news release about the Windfall Lake gold deposit being one of the highest grade resource-stage gold projects in Canada; the significance of results from the new infill drilling and ongoing drill definition and expansion program at the Windfall Lake gold project; the significance of assay results presented in this news release; the deposit remaining open along strike and at depth; potential depth extensions of the mineralized zones down-plunge and at depth; the actual mineralization of local visible gold; the current 800,000 metre drill program; the type of drilling included in the drill program; potential mineralization; the potential to extend mineralization up and down-plunge and at depth at the Windfall Lake gold deposit; the ability to realize upon any mineralization in a manner that is economic; the ability to complete any proposed exploration activities and the results of such activities, including the continuity or extension of any mineralization; and any other information herein that is not a historical fact may be “forward-looking information”. Any statement that involves discussions with respect to predictions, expectations, interpretations, beliefs, plans, projections, objectives, assumptions, future events or performance (often but not always using phrases such as “expects”, or “does not expect”, “is expected”, “interpreted”, “management’s view”, “anticipates” or “does not anticipate”, “plans”, “budget”, “scheduled”, “forecasts”, “estimates”, “believes” or “intends” or variations of such words and phrases or stating that certain actions, events or results “may” or “could”, “would”, “might” or “will” be taken to occur or be achieved) are not statements of historical fact and may be forward-looking information and are intended to identify forward- looking information. This forward-looking information is based on reasonable assumptions and estimates of management of the Corporation at the time such assumptions and estimates were made, and involves known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievements of Osisko to be materially different from any future results, performance or achievements expressed or implied by such forward-looking information. Such factors include, among others, risks relating to the ability of exploration activities (including drill results) to accurately predict mineralization; errors in management’s geological modelling; the ability of Osisko to complete further exploration activities, including drilling; property interests in the Windfall Lake gold project; the ability of the Corporation to obtain required approvals and complete transactions on terms announced; the results of exploration activities; risks relating to mining activities; the global economic climate; metal prices; dilution; environmental risks; and community and non-governmental actions. Although the forward-looking information contained in this news release is based upon what management believes, or believed at the time, to be reasonable assumptions. Osisko cannot assure shareholders and prospective purchasers of securities of the Corporation that actual results will be consistent with such forward-looking information, as there may be other factors that cause results not to be as anticipated, estimated or intended, and neither Osisko nor any other person assumes responsibility for the accuracy and completeness of any such forward-looking information, Osisko does not undertake, and assumes no obligation, to update or revise any such forward-looking statements or forward-looking information contained herein to reflect new events or circumstances, except as may be required by law.

For further information please contact:

John Burzynski
President and Chief Executive Officer
Telephone: (416) 363-8653