Denison Mines(DNN) - 2023 Q2 - Quarterly Report

Exhibit 99.1 FORM 51-102F3 MATERIAL CHANGE REPORT Item Name and Address of Company 1: Denison Mines Corp. (“Denison” or the “Company”) 1100 – 40 University Avenue Toronto, ON M5J 1T1 Item Date of Material Change 2: June 26, 2023 Item News Release 3: A news release announcing the material change was disseminated on June 26, 2023 through the facilities of CNW Group (Cision), a copy of which have been filed under Denison’s profile on SEDAR. Item Summary of Material Change 4: On June 26, 2023, Denison announced ...