Denison Mines Corp. announced an 88% increase in the Indicated Mineral Resources estimated for the Wheeler River project. Denison is also pleased to announce it has increased its interest in the Wheeler River project during 2017 from 60% to 63.3% in accordance with an agreement with its Wheeler River Joint Venture partners, as previously announced on January 10, 2017. The updated mineral resource estimate for Wheeler River is highlighted by a significant increase in the estimated mineral resources for the property's basement-hosted Gryphon uranium deposit. The Gryphon deposit is estimated to contain, above a cut-off grade of 0.2% U3O8, 61.9 million pounds of U3O8 (1,643,000 tonnes at 1.71% U3O8) in Indicated Mineral Resources, plus 1.9 million pounds of U3O8 (73,000 tonnes at 1.18% U3O8) in Inferred Mineral Resources. Wheeler River is also host to the Phoenix deposit, which is estimated to include Indicated Mineral Resources of 70.2 million pounds of U3O8 above a cut-off grade of 0.8% U3O8 (166,000 tonnes at 19.1% U3O8), as disclosed in the Preliminary Economic Assessment for the Wheeler River Uranium Project, Saskatchewan, Canada dated March 31, 2016 and prepared by Ken Reipas, P.Eng of SRK Consulting (Canada) Inc. With this update to the resources estimated for the Gryphon deposit, the combined Indicated Mineral Resources estimated for Wheeler River have increased by 88% to 132.1 million pounds U3O8, which will be used to support the Pre-Feasibility Study ("PFS") initiated for the project in July 2016 and expected to be completed during 2018.