Denison's Wheeler River Summer Program Continues to Expand Phoenix Deposits

TORONTO, ONTARIO--(Marketwire - Aug. 4, 2010) - Denison Mines Corp. (TSX:DML)(NYSE Amex:DNN) ("Denison" or the "Company") is pleased to report results from a further 14 holes of its summer drill program on its Wheeler River property in Saskatchewan. High-grade mineralization at Zone A has been extended 25 metres to the northeast by WR-334, which returned 10.7% eU3O8 over 2.7 metres. The strike length of Zone B has also been extended a further 50 metres to the northeast by hole WR-333, which returned 20.7% eU3O8 over 2.2 metres. Both of these zones continue to remain open along strike. The remainder of the summer program will concentrate on Zones A and B to continue to extend the strike length and support the forthcoming resource study to be completed this year.

The results from this portion of the summer program are shown below.

-----------------------------------------------------------
                                                         GT
                                                      grade
                                                          x
                               Interval       Grade   thick
Hole ID   From (m)   To (m)         (m)   (% eU3O8)    ness
-----------------------------------------------------------
WR-329      397.05   400.25         3.2        0.23     0.7
And         409.35   412.05         2.7        0.22     0.6
WR-330      403.45   404.45         1.0         1.4     1.4
WR-331                  No significant results
WR-332                  No significant results
WR-333      397.55   399.75         2.2        20.7    45.5
WR-334      407.75   410.45         2.7        10.7    28.9
WR-335      402.45   403.75         1.3         3.6     4.7
WR-336                  No significant results
WR-337      411.65   413.85         2.2        0.13     0.3
WR-338                  No significant results
WR-339                  No significant results
WR-340                  No significant results
WR-341A     400.30   401.10         0.8        0.27     0.2
WR-342      407.50   411.80         4.3        28.3   121.7
-----------------------------------------------------------

Zone A

An additional nine holes totalling approximately 4,111 metres continued to define Zone A. On the northeastern boundary, drill hole WR-334 returned 10.7% eU3O8 over 2.7 metres and extended this boundary at least 25 metres. Two holes (WR-335 and 338) tested the current southerly boundary of Zone A. Drill hole WR-335 returned 3.62% eU3O8 over 1.3 metres from 402.45 metres. With this intersection, Zone A is continuously mineralized over a width of 45.0 metres in this area and remains open. Drill hole WR-338 however did not return any significant results. Hole WR-342 was drilled on section 12.5 metres northwest of hole WR-311, which previously reported 6.66% U over 6.5 metres, and returned 28.28% over 4.3 metres from 407.5 metres. This hole tested a relatively un-drilled part of Zone A, where the section spacing was 70 metres, again demonstrating the presence of a high-grade "core" of mineralization. The remaining five holes tested the extreme northeast and northwest boundaries.

Holes WR-332 and 340 did not return any significant results. WR-340 attempted to test the extent of Zone A a further 25 metres to the northeast, and while intense alteration of the type usually associated with mineralization was intersected in the sandstone, no graphitic pelite was noted in the basement.

Zone B

Three holes totalling 1,404 metres tested Zone B. Drill hole WR-333 reported 20.7% eU3O8 over 2.2 metres from 397.55 metres. This hole was located 50 metres to the northeast of the discovery hole WR-258, which returned 11.82% U3O8 over 5.5 metres from 397.0 metres. This result has extended the strike of this important mineralized zone a further 50 metres. Two holes, WR-331 and WR-336, tested on section at 10-metre step outs to both the northwest and southeast of discovery hole WR-258, did not intersect any significant mineralization, indicating a narrowing of the mineralization in this area.

Gap Area

The area between Zone A and Zone B, which was approximately 200 metres in length had very few drill holes to test the potential for Zones A and B converging. WR-341A tested the midpoint of the "gap" between Zones A and B and returned 0.27% eU3O8 over 0.8 metres from 400.3 metres. The mineralization, sandstone structures and observed alteration in this hole indicate that this area is probably continuously mineralized but may be narrower at this location and the optimum zone is proving difficult to target from surface. WR-339 was located 50 metres to the SW of the last mineralized hole on Zone B, WR-266 at 3.78% U3O8 over 1.0 metres, and returned no significant mineralization.

Summer 2010 Overview

A total of 31 holes have now been drilled for 14,813 metres. The results of the summer program are shown on the attached map. The average depth to the unconformity for the summer program is 396.0 metres. Five holes have been drilled on geophysical targets and thirteen, three, two, and four holes have been drilled on Zones A, B, C, and D, respectively. A further four holes tested the gaps between the mineralized zones. The planned 45 hole, 20,000 metre drill program will likely end in late August.

The Phoenix deposits are located on the Wheeler River property which is located between the McArthur River Mine and Key Lake mill complex. Denison is the operator and holds a 60% interest in the Wheeler River Property. Cameco Corporation holds a 30% interest and JCU (Canada) Exploration Company, Limited holds the remaining 10% interest. All previous and current drill results from Phoenix have been tabulated and are presented on our website at www.denisonmines.com.

The technical information contained in this press release related to the above described exploration activities is reported and verified by William C. Kerr, Denison's Vice President, Exploration, who is a qualified person as defined by 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 19, 2010 filed under the Company's profile on the SEDAR website. All drill holes reported to date were drilled at either -80 or -90 degrees, (except for WR-325 which was drilled at -75) and while the exact attitude of the mineralization remains uncertain, it is believed, at this time, that the mineralized intervals represent near true widths. All equivalent uranium values reported at a 1.0% eU3O8 cut-off unless otherwise noted.