Exhibit 99.1 

Denison Mines Corp. 1100 – 40 University Ave Toronto, ON M5J 1T1 www.denisonmines.com

PRESS RELEASE

Denison CFO on Temporary Medical Leave of Absence,

Interim CFO Appointed

Toronto, ON – September 1, 2023. Denison Mines Corp. (‘Denison’ or the ‘Company’) (TSX: DML, NYSE American: DNN) reports that Mac McDonald (CPA), the Company’s Chief Financial Officer, is on a temporary medical leave of absence. Elizabeth Sidle (CPA, CA), who currently serves as Denison’s Vice President Finance, has also been appointed Interim Chief Financial Officer.

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. In mid-2023, a Feasibility Study was completed for Wheeler River’s Phoenix deposit as an In-Situ Recovery (‘ISR’) mining operation, and an update to the previously prepared PFS 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 (‘EIS’) submitted for regulator and public review October 2022.

Denison’s interests in Saskatchewan also include a 22.5% ownership interest in the McClean Lake Joint Venture, which owns several uranium deposits and the McClean Lake uranium mill, 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 Túé (‘THT’) 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.

Throughits 50% ownership of JCU (Canada) Exploration Company, Ltd (‘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 approximately 285,000 hectares in the Athabasca Basin region.

For more information, please contact:

David Cates	(416) 979-1991 ext. 362
President and Chief Executive Officer
Elizabeth Sidle	(416) 979-1991 ext. 311
Vice President Finance & Interim Chief Financial Officer
Follow Denison on Twitter	@DenisonMinesCo

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.

Cautionary Statement Regarding Forward-Looking Statements

Certain information contained in this press release constitutes ‘forward-looking information’, within the meaning of the applicable United States and Canadian legislation concerning the business, operations and financial performance and condition of Denison. Generally, these forward-looking statements can be identified by the use of forward-looking terminology such as ‘plans’, ‘expects’, ‘budget’, ‘scheduled’, ‘estimates’, ‘forecasts’, ‘intends’, ‘anticipates’, or ‘believes’, or the negatives and/or variations of such words and phrases, or state that certain actions, events or results ‘may’, ‘could’, ‘would’, ‘might’ or ‘will be taken’, ‘occur’, ‘be achieved’ or ‘has the potential to’.

In particular, this press release contains forward-looking information pertaining to the following: expectations with respect to the leave of absence and Interim CFO appointment; interpretations, projections and plans with respect to exploration, development and expansion of the Company’s projects; expectations regarding Denison’s joint venture ownership interests; and expectations regarding the continuity of its agreements with third parties.

Forward looking statements are based on the opinions and estimates of management as of the date such statements are made, and they are subject to known and unknown risks, uncertainties and other factors that may cause the actual results, level of activity, performance or achievements of Denison to be materially different from those expressed or implied by such forward-looking statements. Denison believes that the expectations reflected in this forward-looking information are reasonable, but no assurance can be given that these expectations will prove to be accurate and results may differ materially from those anticipated in this forward-looking information. For a discussion in respect of risks and other factors that could influence forward-looking events, please refer to the factors discussed in the Company’s Annual Information Form dated March 27, 2023 under the heading ‘Risk Factors’. These factors are not, and should not be, construed as being exhaustive.

Accordingly, readers should not place undue reliance on forward-looking statements. The forward-looking information contained in this press release is expressly qualified by this cautionary statement. Any forward-looking information and the assumptions made with respect thereto speaks only as of the date of this press release. Denison does not undertake any obligation to publicly update or revise any forward-looking information after the date of this press release to conform such information to actual results or to changes in Denison's expectations except as otherwise required by applicable legislation.