Osisko Files PEA Technical Report for Windfall Project

TORONTO, Aug. 01, 2018 -- Osisko Mining Inc. (TSX:OSK; "Osisko" or the "Corporation") is pleased to announce the filing of an independent preliminary economic assessment technical report on its Windfall project, which has been prepared in accordance with National Instrument 43-101 – Standards of Disclosure for Mineral Projects. The technical report, entitled "Preliminary Economic Assessment of the Windfall Lake Project, Lebel-sur-Quévillon, Québec, Canada" and dated August 1, 2018 (effective date of July 12, 2018), has been prepared for Osisko by BBA Inc., InnovExplo Inc., Golder Associates Ltd., WSP Canada Inc. and SNC-Lavalin Stavibel Inc. (the "Windfall PEA"). The Windfall PEA is available on SEDAR (www.sedar.com) under Osisko's issuer profile.

Osisko's news release dated July 17, 2018 (entitled "Osisko Delivers Positive PEA for Windfall project") summarized certain key results, assumptions and estimates contained in the Windfall PEA. The Corporation is pleased to report that there are no material differences between the key results, assumptions and estimates contained in the Windfall PEA and Osisko's news release dated July 17, 2018.

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% in the high-grade Windfall 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 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 Jonpol and Garrcon deposits on the Garrison property. The Corporation also holds interests and options in a number of additional properties in northern Québec and Ontario.

Cautionary Statement Regarding Technical information
Readers are cautioned that the Windfall PEA is preliminary in nature and includes inferred mineral resources that are too speculative geologically to have economic considerations applied to them that would enable them to be categorize as mineral reserves. There is no certainty that the results, assumptions or estimates in the Windfall PEA will be realized. Mineral resources are not mineral reserves and do not have demonstrated economic viability.

For further information please contact:
John Burzynski
President and Chief Executive Officer
Telephone: (416) 363-8653