An anonymous director reports

DENISON ANNOUNCES FILING OF TECHNICAL REPORT FOR WHEELER RIVER

Denison Mines Corp. has filed its technical report supporting the results of: (i) the feasibility study (Phoenix FS) completed for in situ recovery (ISR) mining of the high-grade Phoenix uranium deposit (Phoenix)l and (ii) a cost update (Gryphon update) to the 2018 prefeasibility study (2018 PFS) for conventional underground mining of the basement-hosted Gryphon uranium deposit. The report is titled "NI 43-101 Technical Report on the Wheeler River Project Athabasca Basin, Saskatchewan, Canada," dated Aug. 8, 2023, with an effective date of June 23, 2023.

The parties to the Wheeler River Joint Venture are Denison (operator) and JCU (Canada) Exploration Company Limited ("JCU"). Denison has an effective 95% ownership interest in the WRJV (90% directly, and 5% indirectly through a 50% ownership in JCU).

This press release constitutes a "designated news release" for the purposes of the Company ' s prospectus supplement dated September 28, 2021 to its short form base shelf prospectus dated September 16, 2021.

Wheeler River Technical Report

The Technical Report will be posted on the Company's website and is or will be available under its profile on SEDAR and on EDGAR.

This report supports the disclosure made by the Company in its news release dated June 26, 2023, "Denison reports significant increase in economic results for Wheeler River" (the "News Release"). There are no material differences in the Technical Report from the information disclosed in the News Release.

As outlined below and in the News Release, (i) the Phoenix FS confirms robust economics and the technical viability of an ISR uranium mining operation with low initial capital costs and a high rate of return, and (ii) the Gryphon PFS Update demonstrates that the underground development of Gryphon is a positive potential future use of cash flows generated from Phoenix, as it is able to leverage existing infrastructure to provide an additional source of low-cost production.

Front-End Engineering Design

The completion of the Phoenix FS is a key milestone to support the next phases of engineering design for the project. The front-end engineering design ("FEED") phase has already commenced and is expected to be completed before the end of the year. The objective of the FEED phase is to assess optimization opportunities and identify key long lead procurement requirements. Including the detailed design phase, project engineering efforts are expected to be completed in approximately two years.

Following a future final investment decision ("FID") and completion of engineering, construction is expected to last another two years. Assuming sufficient funding is secured by the owners of the WRJV, engineering and other pre-construction activities advance per plan, and timely receipt of required regulatory approvals, first production is currently anticipated to occur in 2027 or 2028.

About Denison

Denison is a uranium exploration and development company with interests focused in the Athabasca Basin region of northern Saskatchewan, Canada. The Company has an effective 95% interest in its flagship Wheeler River Uranium Project, which is the largest undeveloped uranium project in the infrastructure rich eastern portion of the Athabasca Basin region of northern Saskatchewan. The Feasibility Study was completed for Wheeler River's Phoenix deposit as an ISR mining operation, and the Gryphon Update to the previously prepared Pre-Feasibility Study was completed for Wheeler River's Gryphon deposit as a conventional underground mining operation. Based on the respective studies, both deposits have the potential to be competitive with the lowest cost uranium mining operations in the world. Permitting efforts for the planned Phoenix ISR operation commenced in 2019 and have advanced significantly, with licensing in progress and a draft Environmental Impact Statement submitted for regulatory and public review in October 2022.

Denison's interests in Saskatchewan also include a 22.5% ownership interest in the McClean Lake Joint Venture, which comprises several uranium deposits and the McClean Lake uranium mill that is contracted to process the ore from the Cigar Lake mine under a toll milling agreement, plus a 25.17% interest in the Midwest Main and Midwest A deposits and a 67.41% interest in the Tthe Heldeth Tue ('THT', formerly J Zone) and Huskie deposits on the Waterbury Lake property. The Midwest Main, Midwest A, THT and Huskie deposits are located within 20 kilometres of the McClean Lake mill.

Through its 50% ownership of JCU, Denison holds additional interests in various uranium project joint ventures in Canada, including the Millennium project (JCU, 30.099%), the Kiggavik project (JCU, 33.8118%) and Christie Lake (JCU, 34.4508%).

Denison's exploration portfolio includes further interests in properties covering ~285,000 hectares in the Athabasca Basin region.

Denison is also engaged in post-closure mine care and maintenance services through its Closed Mines group, which manages Denison's reclaimed mine sites in the Elliot Lake region and provides related services to certain third-party projects.

Qualified Persons

The technical information contained in this release has been reviewed and approved by Mr. Chad Sorba, P.Geo, Denison's Director, Technical Services, and Mr. Andrew Yackulic, P. Geo., Denison's Director, Exploration, each of whom is a Qualified Person in accordance with the requirements of NI 43-101.

We seek Safe Harbor.