Toronto, Ontario, May 3, 2017 — Primero Mining Corp. (“Primero” or the “Company”) (TSX:P) (NYSE:PPP) today reported operating and financial results for the first quarter ended March 31, 2017, and provided 2017 operating guidance. Highlights: Q1 2017 Production Affected by Strike at San Dimas: Total production of 26,733 gold equivalent ounces1 , comprised of 10,118 ounces of gold and 0.62 million ounces of silver from San Dimas, and 14,413 ounces of gold from Black Fox, 26% lower than the 36,158 gold equivalent ounces produced in Q1 2016. Consolidated Q1 2017 total cash costs2 were $827 per gold equivalent ounce, with consolidated all-in sustaining costs3 (“AISC”) of $1,335. $5.2 million for standby site costs incurred during the San Dimas strike have been excluded from cash costs. San Dimas Strike Ends With New CBA, San Dimas Phased Reset Underway: Strike action taken by San Dimas unionized employees negatively affected Q1 production, resulting in only 45 operating days in the quarter. The strike ended on April 13 with the agreement of a new Collective Bargaining Agreement (‘‘CBA’’), effective over a period of two years. Primero believes the new CBA allows for a competitive cost structure aligned to the future success of San Dimas operations. A phased restart of the San Dimas operation is currently underway, and the mine expects to produce between 90,000 and 110,000 gold equivalent ounces during 2017. Financial Results Benefit from Lower Operating Expenses: Despite lower gold and silver production, higher earnings were realized in Q1 2017 from lower operating expenses, depreciation and depletion as a result of the strike. The Company recognized net income of $13.5 million ($0.07 per share) due to a $19.5 million deferred income tax recovery in Q1 2017 mainly resulting from the effect of the revaluation of the Mexican peso compared to the U.S. dollar. Adjusted net income4 was $nil ($nil per share) for Q1 2017. 2 2017 Production Guidance: Primero expects to produce between 140,000 and 170,000 gold equivalent ounces in 2017. Total production in 2017 is expected to be lower than in the previous year due to operating time lost during the San Dimas strike, and the phased restart approach. Total cash costs are expected to be in the range of $700 to $850 per gold equivalent ounce, with AISC between $1,200 and $1,400 per gold ounce. AISC includes a $25 million incremental reset investment in San Dimas for exploration and development to position the mine for future profitability and sustainability.