Denison Reports 3.7% eU3O8 Over 3.9 Metres From Initial Follow Up Drilling at New High-Grade Basement Uranium Discovery at Waterbury Lake

TORONTO, ONTARIO--(Marketwired - Aug. 22, 2017) - Denison Mines Corp. ("Denison" or the "Company") (TSX:DML)(NYSE MKT:DNN)(NYSE American:DNN) is pleased to report that drill hole WAT17-446A returned a mineralized interval of 3.7% eU3O8 over 3.9 metres (from 305.7 to 309.6 metres), including 7.8% eU3O8 over 1.8 metres (from 307.0 to 308.8 metres). Drill hole WAT17-446A was the fourth hole completed as part of the summer 2017 drilling program at the Waterbury Lake property and was drilled approximately 50 metres along strike to the west of WAT17-443, which intersected 1.1% eU3O8 over 0.8 metres (see Denison's Press Release dated August 1st, 2017).