Denison Announces 22.1 Metres of High-Grade Mineralization From Gryphon D Series as Winter Drilling Wraps Up at Wheeler River

Denison Mines Corp.

TORONTO, ONTARIO--(Marketwired - April 20, 2017) - Denison Mines Corp. ("Denison" or the "Company") (TSX:DML)(NYSE MKT:DNN) is pleased to report additional high-grade intersections from the Gryphon D series lenses of mineralization, which remain outside of the resources estimated for the Gryphon deposit in late 2015. The Gryphon deposit accompanies the Phoenix deposit on the Company's 60% owned Wheeler River project, which is the largest undeveloped high-grade uranium project in the infrastructure rich eastern portion of the Athabasca Basin. In addition, the Company is pleased to report radiometric equivalent grade results ("eU3O8") from the final drill holes completed during the winter 2017 drill program at Wheeler River.