Denison Announces Appointment of Tim Gabruch as Vice President Commercial

Denison Mines Corp.

1100 – 40 University Ave

Toronto, ON M5J 1T1

www.denisonmines.com

@DenisonMinesCo

PRESS RELEASE

DENISON ANNOUNCES APPOINTMENT OF

TIM GABRUCH AS VICE PRESIDENT COMMERCIAL

Toronto, ON – September 5, 2018 Denison Mines Corp. (“Denison” or the “Company”) (TSX: DML) (NYSE

American: DNN) is pleased to announce the appointme nt of Mr. Tim Gabruch, as Vice President

Commercial. Tim will be based in the Company’s Saskatoon office and will be tasked with building an “end

to end” sales, marketing and commercial function th at is consistent with the Company’s entrepreneurial

culture and long-term strategy surrounding the futu re development of its flagship Wheeler River

uranium project.

Tim has nearly two and a half decades of experience in the uranium mining and nuclear energy industries,

having spent 23 years with Cameco Corporation (“Cam eco”) in various marketing and corporate

development roles. He served as Vice President Mark eting, from 2011 to 2017, leading a diverse team

responsible for strategy development, sales and mar keting, administration, and inventory and logistics

management – resulting in the successful delivery of more than 30 million pounds U3O8 annually. Through

his career, Tim has worked directly with nuclear ut ilities from around the world, including having spe nt 8

years at Cameco’s previous marketing and sales subsidiary in Minneapolis, USA. Tim also has experience

serving the World Nuclear Association’s predecessor organization, the Uranium Institute, during a

secondment, and as a board member of the Saskatchew an Trade and Export Partnership (STEP), a joint

government/private non-profit organization that champions the province’s export industry.

David Cates, President and CEO of Denison, commented “The uranium industry is small, and it is rare

that we would have an opportunity to add someone wi th Tim’s industry specific experience and

background to our executive leadership team. We ar e pleased to have Tim join the Denison team

and we are looking forward to building a commercial and marketing function fitting with our

Company’s culture and strategy – particularly as we begin to organize our team for the next steps

following the completion of the Wheeler River Pre-F easibility Study, which is expected to be

completed by the end of the third quarter.”

Mr. Gabruch will also be assuming responsibility for all commercial aspects associated with the Company’s

Management Services Agreement with Uranium Participation Corp. (“UPC”)(TSX: U), as Mr. Scott Melbye,

who currently serves as VP Commercial to UPC, is mo ving on from his part-time consulting role with the

Company to pursue other opportunities in which he is involved.

About Denison

Denison is a uranium exploration and development company with interests focused in the Athabasca Basin

region of northern Saskatchewan, Canada. In additio n to its 63.3% owned Wheeler River project, which

ranks as the largest undeveloped high-grade uranium project in the infrastructure rich eastern portion of

the Athabasca Basin region, Denison's Athabasca Basin exploration portfolio consists of numerous projects

covering approximately 321,000 hectares. Denison's interests in Athabasca Basin also include a 22.5%

ownership interest in the McClean Lake joint ventur e (“MLJV”), which includes several uranium deposits

and the McClean Lake uranium mill, which is current ly processing ore from the Cigar Lake mine under a

toll milling agreement, plus a 25.17% interest in the Midwest and Midwest A deposits, and a 65.45% interest

in the J Zone deposit and Huskie discovery on the W aterbury Lake property. Each of Midwest, Midwest A,

J Zone and Huskie are located within 20 kilometres of the McClean Lake mill.

Denison is also engaged in mine decommissioning and environmental services through its Denison

Environmental Services division and is the manager of Uranium Participation Corp., a publicly traded

company which invests in uranium oxide and uranium hexafluoride.

For more information, please contact

David Cates (416) 979-1991 ext. 362

President and Chief Executive Officer

Sophia Shane (604) 689-7842

Investor Relations

Follow Denison on Twitter @DenisonMinesCo

Cautionary Statement Regarding Forward-Looking Statements

Certain information contained in this press release constitutes "forward-looking information", within the meaning of the United States

Private Securities Litigation Reform Act of 1995 an d similar Canadian legislation concerning the busin ess, operations and financial

performance and condition of Denison. Generally, th ese 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 c ontains forward-looking information

pertaining to the following: the anticipated role and objectives to be achieved with the creating of a Vice President Commercial position

and the appointment of Tim Gabruch; the departure of Mr. Melbye; plans and objectives with respect to preparing a PFS to assess on a

preliminary basis the potential for project development; and Denison’s percentage interest in its properties and its plans and agreements

with its joint venture partners

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, performance or achievements

of Denison to be materially different from those ex pressed or implied by forward-looking statements. D enison 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 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 Denison's Annual Information Form dated

March 27, 2018 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 .