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Denison Announces Filing of Technical Report FOR Wheeler River

Resource Estimates Technical Reports (NI 43-101)

Denison Mines Corp.

1100 – 40 University Ave

Toronto, ON M5J 1T1

www.denisonmines.com

@DenisonMinesCo

PRESS RELEASE

DENISON ANNOUNCES FILING OF TECHNICAL REPORT

FOR WHEELER RIVER

Toronto, ON – March 16, 2018 Denison Mines Corp. (“Denison” or the “Company”) (D ML: TSX, DNN:

NYSE MKT) today announces that it filed a technical report under Canadian Securities Administrators'

National Instrument 43-101 Standard of Disclosure for Mineral Projects for its 63.3% owned Wheeler River

Project in Saskatchewan titled "Technical Report wi th an Updated Mineral Resource Estimate for the

Wheeler River Property, Northern Saskatchewan, Cana da" dated March 15, 2018 with an effective date of

March 9, 2018.

The technical report is posted on the Company's web site at www.denisonmines.com and is available under

its profile on SEDAR at www.sedar.com and on EDGAR at www.sec.gov/edgar.shtml.

This report supports the disclosure made by the Com pany in its news release dated January 31, 2018,

"Denison announces 88% increase in indicated resour ces at Wheeler River with updated mineral resource

estimate for the Gryphon deposit” (the "News Releas e") and there are no material differences in the

technical report from the information disclosed in the News Release.

As outlined in the News Release, the updated minera l resource estimate for Wheeler River is highlighte d

by a significant increase in the estimated mineral resources for the property’s basement-hosted Grypho n

uranium deposit and an overall 88% increase in the Indicated Mineral Resources estimated for the Wheel er

River project.

Resource Update Highlights:

• The Gryphon deposit is estimated to contain, above a cut-off grade of 0.2% U 3O8, 61.9 million

pounds of U 3O8 (1,643,000 tonnes at 1.71% U 3O8) in Indicated Mineral Resources, plus 1.9 million

pounds of U3O8 (73,000 tonnes at 1.18% U3O8) in Inferred Mineral Resources.

• Wheeler River is also host to the Phoenix deposit, which is estimated to include Indicated Mineral

Resources of 70.2 million pounds of U 3O8 above a cut-off grade of 0.8% U 3O8 (166,000 tonnes at

19.1% U3O8).

• With this update to the resources estimated for th e Gryphon deposit, the combined Indicated

Mineral Resources estimated for Wheeler River have increased by 88% to 132.1 million pounds of

U3O8 (1,809,000 tonnes at 3.3% U 3O8), which will be used to support the Pre-Feasibilit y Study

("PFS") initiated for the project in July 2016 and expected to be completed during 2018.

Qualified Persons

The technical report was authored by Mr. Mark Mathi sen, C.P.G. of Roscoe Postle Associates Inc. and Ke n

Reipas, P.Eng of SRK Consulting (Canada) Inc., inde pendent Qualified Persons in accordance with the

requirements of NI 43-101.

The technical information contained in this release has been reviewed and approved by Mr. Dale Verran,

MSc, P.Geo, Pr.Sci.Nat., Denison's Vice President, Exploration, who is a Qualified Person in accordanc e

with the requirements of NI 43-101.

About Denison

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

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

hosts the high-grade Phoenix and Gryphon uranium de posits, Denison's exploration portfolio consists of

numerous projects covering approximately 351,000 he ctares in the Athabasca Basin region, including

approximately 316,000 hectares in the infrastructur e rich eastern portion of the Athabasca Basin. Deni son's

interests in Saskatchewan also include a 22.5% owne rship interest in the McClean Lake joint venture

(“MLJV”), which includes several uranium deposits and the McClean Lake uranium mill, which is currentl y

processing ore from the Cigar Lake mine under a tol l milling agreement, plus a 25.17% interest in the

Midwest and Midwest A deposits, and a 64.22% intere st in the J Zone deposit and Huskie discovery on th e

Waterbury Lake property. Each of Midwest, Midwest A , J Zone and Huskie are located within 20 kilometre s

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 and similar Canadian legislation concer ning the

business, operations and financial performance and condition of Denison.

Generally, these forward-looking statements can be identified by the use of forward-looking terminolog y such as

“plans”, “expects”, “budget”, “scheduled”, “estimates”, “forecasts”, “intends”, “anticipates”, or “believes”, or the negatives

and / or variations of such words and phrases, or s tate 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 pres s release contains

forward-looking information pertaining to the resul ts of, and estimates, assumptions and projections p rovided in, the

technical report, and expectations regarding the co mpletion of a PFS. Statements relating to "mineral resources" are

deemed to be forward-looking information, as they i nvolve the implied assessment, based on certain est imates and

assumptions that the mineral resources described can be profitably produced in the future.

Forward looking statements are based on the opinion s and estimates of management as of the date such s tatements

are made, and they are subject to known and unknown risks, uncertainties and other factors that may ca use the actual

results, level of activity, performance or achievem ents of Denison to be materially different from tho se expressed or

implied by such forward-looking statements. Denison believes that the expectations reflected in this f orward-looking

information are reasonable but there can be no assu rance that such statements will prove to be accurat e and may

differ materially from those anticipated in this fo rward looking information. For a discussion in resp ect of risks and other

factors that could influence forward-looking events , please refer to the “Risk Factors” in Denison’s Annual Information

Form dated March 23, 2017 available under its profi le at www.sedar.com and its Form 40-F available at

www.sec.gov/edgar.shtml . These factors are not, and should not be construed as being exhaustive.

Accordingly, readers should not place undue relianc e on forward-looking statements. The forward-lookin g information

contained in this press release is expressly qualif ied by this cautionary statement. Any forward-looki ng information and

the assumptions made with respect thereto speaks on ly as of the date of this press release. Denison d oes 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 its expectations except as otherwise re quired by

applicable legislation.

Cautionary Note to United States Investors Concerni ng Estimates of Measured, Indicated and Inferred Mi neral

Resources: This press release may use the terms “measured”, “i ndicated” and “inferred” mineral resources. United

States investors are advised that while such terms are recognized and required by Canadian regulations , the United

States Securities and Exchange Commission does not recognize them. “Inferred mineral resources” have a great

amount of uncertainty as to their existence, and as to their economic and legal feasibility. It cannot be assumed that all

or any part of an inferred mineral resource will ever be upgraded to a higher category. Under Canadian rules, estimates

of inferred mineral resources may not form the basi s of feasibility or other economic studies. United States investors

are cautioned not to assume that all or any part of measured or indicated mineral resources will ever be

converted into mineral reserves. United States inve stors are also cautioned not to assume that all or any part

of an inferred mineral resource exists, or is economically or legally mineable.