(Montreal, QC, January 29, 2014) — Osisko Mining Corporation (“Osisko” or the “Company“) (TSX: OSK; Deutsche Boerse: EWX) announced today that it has filed with Canadian securities regulatory authorities and commenced the mailing of its directors’ circular (the “Directors’ Circular“) in response to the hostile take-over bid (the “Goldcorp Offer“) launched by Goldcorp Inc. (“Goldcorp“) on January 14, 2014.

The Directors’ Circular contains the unanimous recommendation of the board of directors of Osisko (the “Board“), following the recommendation of the special committee of independent directors (the “Special Committee“) and advice from its financial and legal advisors, that Osisko shareholders (“Osisko Shareholders“) REJECT the Goldcorp Offer and NOT TENDER their Osisko shares to the Goldcorp Offer.

In making its recommendation, the Board considered numerous factors, including the recommendation of the Special Committee and opinions prepared by BMO Capital Markets and Maxit Capital LP with respect to the financial inadequacy of the Goldcorp Offer. The full texts of the opinions are attached as Appendix “A” and Appendix “B” to the Directors’ Circular. Osisko Shareholders are urged to read the Directors’ Circular in its entirety. A copy of the Directors’ Circular is available on the System for Electronic Document Analysis and Retrieval (SEDAR) website at: www.sedar.com under the Company’s profile.

Further to Osisko’s news release dated January 20, 2014, the following is a summary of the principal reasons for the decision by the Board to recommend REJECTING the Goldcorp Offer, which are described in greater detail in the Directors’ Circular:

• the Goldcorp Offer fails to recognize the strategic value of Osisko’s world-class asset base. Osisko’s Canadian Malartic mine is a world-class gold mine, with superior scale and lower costs relative to many of the producing assets held by the five largest North American domiciled gold producers;

• the timing of the Goldcorp Offer is opportunistic. The Goldcorp Offer has been opportunistically timed to occur before the Canadian Malartic mine enters what Osisko expects will be its most productive years;

• Goldcorp’s prior proposals to Osisko would have all been value destructive to Osisko Shareholders;

• Goldcorp is offering an immaterial premium which is well below those paid in relevant precedent transactions. Goldcorp is offering a meager 15% premium based on the closing prices of Osisko and Goldcorp on the TSX as at January 10, 2014 (the last trading day prior to the announcement of the Goldcorp Offer) which is substantially below the premiums paid in other relevant metals and mining transactions;

• Goldcorp is offering a discount to the current trading price of Osisko shares. Since the January 13, 2014 announcement of Goldcorp’s intention to make the Goldcorp Offer, Osisko shares have consistently traded at prices above the implied price of the Goldcorp Offer;

• Goldcorp is offering a transaction multiple significantly below precedent transaction multiples paid for large-scale gold producers. The Goldcorp Offer represents a significant discount to the street estimates of Price/Net Asset Value multiples paid for other large-scale gold producers and the Price/Net Asset Value multiple Goldcorp itself has paid in its most material acquisitions;

• Osisko Shareholders are not being adequately compensated for the risks and uncertainties that are inherent in the Goldcorp shares. Goldcorp shares carry greater geopolitical risk, higher development risk, have significant exposure to base metals and are richly valued. Goldcorp has also disclosed that its primary asset, the Peñasquito mine in Mexico, is subject to significant legal risk;

• companies with a high-quality single asset often generated superior returns, versus highly diversified gold companies;

• the Goldcorp Offer is financially inadequate;

• the directors and senior officers of Osisko have indicated to Osisko that they do not intend to tender any of their Osisko shares to the Goldcorp Offer;

• the Goldcorp Offer is not a “Permitted Bid” under Osisko’s shareholder rights plan;

• the Board is aggressively pursuing value-maximizing alternatives. Tendering Osisko shares to the Goldcorp Offer before the Board and its advisors have had an opportunity to fully explore all available strategic alternatives to the Goldcorp Offer may preclude the possibility of a superior alternative transaction emerging; and

• the Goldcorp Offer is highly conditional.

For these, and other, reasons, the Board recommends that the Osisko Shareholders REJECT the Goldcorp Offer and NOT TENDER their Osisko shares to the Goldcorp Offer.

About Osisko Mining Corporation

Osisko operates the Canadian Malartic mine in Malartic, Québec and is pursuing exploration on a number of properties in Ontario, Canada and Mexico.

How to Withdraw Shares from the Goldcorp Offer

Shareholders who have questions or who may have already tendered their shares to the Goldcorp Offer and wish to withdraw them, may do so by contacting our Information Agent, Laurel Hill, Toll Free (North America): 1-877-452-7184, Outside North America Call Collect: 416-304-0211 or email: [email protected].

Forward-Looking Statements

Certain statements contained in this press release may constitute “forward-looking statements”. All statements in this press release, other than statements of historical fact, that address events or developments that Osisko expects to occur, are forward-looking statements. Forward-looking statements are statements that are not historical facts and are generally, but not always, identified by the words “expects”, “plans”, “anticipates”, “believes”, “intends”, “estimates”, “projects”, “potential”, “scheduled” and similar expressions, or that events or conditions “will”, “would”, “may”, “could” or “should” occur including, but not limited to: the value of the assets of Osisko (including Canadian Malartic Mine) and Goldcorp; the future financial performance of Osisko and Goldcorp; risks relating to properties, development projects and producing mines of Osisko and Goldcorp; the accuracy of reserve and resource estimates, grades, mine life and cash cost estimates; whether mineral resources can be developed; interest and exchange rates; timing and receipt of regulatory and governmental approvals; availability of financing for Osisko’s development for future projects; the successful completion of new development projects, planned expansions or other projects within the timelines anticipated and at anticipated production levels; Osisko’s estimation of its costs of production, expected production and productivity levels; accuracy of Osisko’s resource estimate (including with respect to size, grade and recoverability); geological, operational and price assumptions in Osisko’s resource estimate; general economic conditions; changes in laws, rules and regulations applicable to Osisko; competitive conditions in the mining industry; title to mineral properties; the price of gold and other metals; the strength of the economic fundamentals of gold relative to other base metals; and whether or not any alternative transaction superior to the Goldcorp Offer may emerge.