Denison Expands the 489 Zone at Wheeler River

TORONTO, ONTARIO--(Marketwired - April 24, 2013) - Denison Mines Corp. (TSX:DML)(NYSE MKT:DNN) ("Denison" or the "Company") has completed a second fence of drilling in the vicinity of drill hole WR-489 that has extended unconformity uranium mineralization along strike by 65 metres. The area is 2.1 kilometres northeast of the Phoenix deposits and is now being referred to as the 489 Zone.

Wheeler River

The winter drill program is now complete at Wheeler River. A total of 14,577 metres was drilled in 27 drill holes. Sixteen of the drill holes were completed on five different exploration target areas (489 Zone, K Zone, Phoenix North, 232 area and the REA area) on the Wheeler River property. The highlight of the program was the discovery of new unconformity related uranium mineralization at the 489 Zone. Located approximately 2.1 kilometres northeast of the Phoenix deposits the 489 Zone straddles the sub-Athabasca unconformity at a vertical depth of 380 meters below surface, on top of faulted graphitic gneiss. Rock types, alteration and structure are similar to the Phoenix deposits. Mineralization has now been intersected on both drill hole fences completed to date - 65 metres apart, and the zone is open along strike in both directions. A summer drill program is planned to aggressively follow up on these results.

The table below summarizes the mineralized intersections. Figure 1 (http://media3.marketwire.com/docs/dml424-F1.pdf) shows the location of the 489 Zone relative to the Phoenix deposits.

489 Zone Drilling Results

On the other four exploration target areas, encouraging geochemistry and alteration was observed at Phoenix North, and the K Zone. Further work is required to follow up on these results - some of which will be a part of this summer's activities. No significant mineralization, alteration or geochemistry was observed at the 232 and REA areas.

The remainder of the winter program consisted of four drill holes to infill two small Inferred portions of the Phoenix A deposit. As previously reported, high grade uranium mineralization was intersected in all four of these drill holes (see news release March 14, 2013). Another five drill holes explored for basement mineralization proximal to the north end of the Phoenix A deposit. Although no significant mineralization was intersected, this area remains open for further testing.

The Wheeler River property lies between the McArthur River mine and Key Lake mill complex in the Athabasca Basin in northern Saskatchewan. Denison is the operator and holds a 60% interest in the project. Cameco Corporation holds a 30% interest and JCU (Canada) Exploration Company, Limited holds the remaining 10% interest.

Hatchet Lake

As reported previously, uranium mineralization was intersected at Hatchet Lake in two drill holes on the northern portion of the Crooked-Richardson Lakes trend. Chemical assays have now been received for this drilling and the best result was in drill hole RL-13-16, which intersected 0.45% U₃O₈ over 2.3 metres beginning at 124.0 metres down the drill hole. Further drilling is required to follow up on these results.

Qualified Person

The disclosure of a scientific or technical nature contained in this news release was prepared by Steve Blower, P.Geo., Denison's Vice President, Exploration, who is a Qualified Person in accordance with the requirements of NI 43-101. For a description of the quality assurance program and quality control measures applied by Denison, please see Denison's Annual Information Form dated March 13, 2013 filed under the Company's profile on SEDAR at www.sedar.com.

About Denison

Denison Mines Corp. is a uranium exploration and development company with interests in exploration and development projects in Canada, Zambia and Mongolia. Including the world class Phoenix deposits, located on its 60% owned Wheeler River project, Denison's exploration project portfolio includes 32 projects and totals over 530,000 hectares in the Eastern Athabasca Basin region of Saskatchewan. Denison's interests in Saskatchewan also include a 22.5% ownership interest in the McClean Lake Joint Venture, which includes several uranium deposits and the McClean Lake uranium mill, one of the world's largest uranium processing facilities, and a 25.17% interest in the Midwest deposit, which is located 15 kilometres from the McClean Lake mill. Internationally, Denison owns 100% of the conventional heap leach Mutanga project, in Zambia, and an 85% interest in the in-situ recovery projects held by the Gurvan Saihan Joint Venture, in Mongolia.

Denison is engaged in mine decommissioning and environmental services through its Denison Environmental Services (DES) division and is the manager of Uranium Participation Corporation (TSX:U), a publicly traded company which invests in uranium oxide in concentrates and uranium hexafluoride.

Cautionary 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 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" or "does not expect", "is expected", "budget", "scheduled", "estimates", "forecasts", "intends", "anticipates" or
"does not anticipate", or "believes", 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".

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 correct and such forward-looking information included in this press release should not be unduly relied upon. This information speaks only as of the date of this press release. In particular, this press release may contain forward-looking information pertaining to the following: the estimates of Denison's mineral reserves and resources; capital expenditure programs; expectations regarding the toll milling of Cigar Lake ores; exploration and development expenditures and reclamation costs; expectations of market prices and costs; supply and demand for uranium; possible impacts of litigation and regulatory actions on Denison; exploration, development and expansion plans and objectives; future royalty and tax payments and rates; Denison's expectations regarding raising capital and adding to its mineral reserves and resources through acquisitions and exploration; and receipt of regulatory approvals, permits and licences under governmental regulatory regimes.

There can be no assurance that such statements will prove to be accurate, as Denison's actual results and future events could differ materially from those anticipated in this forward-looking information as a result of those factors discussed in or referred to under the heading "Risk Factors" in Denison's Annual Information Form dated March 13, 2013, available at http://www.sedar.com, and in its Form 40-F available at http://www.sec.gov, as well as the following: global financial conditions; the ability of Denison to meet its obligations to its creditors and the uncertainty of funding; volatility in the market price of the Company's shares and the risk of dilution from future equity financings; the impact of volatility in uranium prices on the valuation of Denison's mineral reserves and resources and the market price of its shares; public acceptance of nuclear energy and competition from other energy sources; failure to realize benefits from transactions; competition for properties; the imprecision of mineral reserves and resources estimation; Denison's ability to expand and replace its mineral reserves and resources; uncertainty as to reclamation and decommissioning liabilities; reliance on other operators; technical innovation rendering Denison's products and services obsolete; property title risk; liabilities inherent in mining operations and the adequacy of insurance coverage; delays in obtaining permits and licences for development properties; the speculative nature of exploration and development projects; difficulty complying with changing government regulations and policy, including without limitation, compliance with environment, health and safety regulations; uncertainty surrounding Denison's operations in foreign jurisdictions; potential claims of Canada's first nations people; dependence on key personnel; the potential influence of Denison's largest Shareholder, Korea Electric Power Corporation; potential conflicts of interest for the Company's directors who are engaged in similar businesses; and limitations of disclosure and internal controls.

Accordingly, readers should not place undue reliance on forward-looking statements. These factors are not, and should not be construed as being, exhaustive. Statements relating to "mineral reserves" or "mineral resources" are deemed to be forward-looking information, as they involve the implied assessment, based on certain estimates and assumptions that the mineral reserves and mineral resources described can be profitably produced in the future. The forward-looking information contained in this press release is expressly qualified by this cautionary statement. 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.