Denison Mines Corp.: Drilling at Wheeler River Intersects 55% eU3O8 Over 6.0 Metres and Extends High Grade Uranium

TORONTO, ONTARIO, Jun 30 (MARKET WIRE) --
Denison Mines Corp. (TSX: DML)(NYSE Amex: DNN) ("Denison" or the
"Company") is pleased to report that the ongoing summer drill program at
the Wheeler River property in the Athabasca Basin of northern
Saskatchewan has significantly extended the previously known uranium
mineralization on the eastern portion of the Phoenix discovery
(previously called the R Zone) (see attached Map).

Phoenix East

Drill holes WR-272, 273 and 274 have intersected high-grade uranium
mineralization, at a depth of approximately 400 metres ("m"), which has
extended this zone a further 150 m to the northeast to a strike length of
over 250 m (Table 1). The eastern portion of the Phoenix discovery
remains undrilled along strike to the northeast and for at least 150 m to
the southwest where it may continue as part of the western zone.

Table 1. Phoenix East Results (see Map)

----------------------------------------------------------------------------
Hole # From To Interval Probe Grade
(m) (m) (m) (% eU3O8)
----------------------------------------------------------------------------

WR-272 411.5 413.6 2.1 6.75%
And 414.3 414.8 0.5 2.60%

WR-273 403.9 409.9 6.0 55.0%

WR-274 412.5 415.5 3.0 16.9%
And 417.1 417.7 0.6 2.1%
And 418.5 418.9 0.4 2.7%
And 419.1 420.3 1.2 2.9%
And 428.8 430.2 1.4 2.3%
----------------------------------------------------------------------------

Drill hole WR-275, designed to test for the extension of the eastern
zone 50 m to the northeast of drill hole WR-274, is currently in progress.

The intersections in drill holes WR-272 and 273 were unconformity type
and included 5.0 m of massive pitchblende in drill hole WR-273. In drill
hole WR- 274, the high-grade interval was unconformity type
mineralization, with the other four intervals in this drill hole being
stringer zones in intensely altered basement rocks. This is the first
time intense alteration of this type has been encountered in the basement
rocks along the Phoenix mineralized trend.

Phoenix West

The western portion of the Phoenix discovery extends south-westerly from
Line L150 (see Map).

Drill hole WR-270 was drilled to test for unconformity type
mineralization at the southwestern end of the zone. Minor mineralization
was encountered grading 0.35% eU3O8 over 1.4 m from 375.35 m. The
unconformity was intersected 15 m higher than expected and further
testing of this area will be carried out in 2010.

Drill hole WR-271 tested for mineralization in the quartzite ridge to the
northwest of drill hole WR-260. No mineralization of consequence was
intersected in this hole.

The western portion of the Phoenix discovery remains open along the
unconformity in all directions and further drilling is planned in 2010 to
further evaluate the high grade mineralization and intense alteration
zone encountered in the drilling completed to date.

All drill holes reported to date were drilled at -80 degrees, 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 results are reported at a 1.0% eU3O8 cut-off, except for
drill hole WR-270 which is at a 0.05% eU3O8 cut-off, based on industry
standard down hole probing equipment. Assay results for drill holes
WR-270 to 274 will be reported when they have been received.

The 11 drill hole, 5,500 m summer program is ongoing. The remainder of
the program will focus on extending the eastern portion of the Phoenix
mineralization along strike to the northeast in preparation for the
planning of a major resource delineation program to be carried out in
2010.

The Wheeler River Property, which hosts the Phoenix discovery, is located
in the Athabasca Basin between the McArthur River and Key Lake
operations. This discovery has many geological similarities to the
McArthur River deposit but is at a shallower depth.

Denison is the operator of and holds a 60% interest in the Wheeler River
Property. Cameco Corp. holds a 30% interest and JCU (Canada) Exploration
Company, Limited holds the remaining 10% interest.

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 26,
2009 filed under the Company's profile on the SEDAR website.

About Denison

Denison Mines Corp. is an intermediate uranium producer in North America,
with mining assets in the Athabasca Basin region of Saskatchewan, Canada
and the southwest United States including Colorado, Utah, and Arizona.
Further, the Company has ownership interests in two of the four
conventional uranium mills operating in North America today. Denison also
has a strong exploration and development portfolio with large land
positions in the United States, Canada, Mongolia and Zambia.

Cautionary Statements

This news release contains "forward-looking statements", 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.

Forward looking statements include, but are not limited to, statements
with respect to the proposed transactions announced; the development
potential of Denison's properties, including those of its joint ventures;
the future price of uranium; the estimation of mineral reserves and
resources; the realization of mineral reserve estimates, the timing and
amount of estimated future production, costs of production; capital
expenditures; success of exploration activities; permitting time lines
and permitting, mining or processing issues, currency exchange rate
fluctuations, government regulation of mining operations; environmental
risks; unanticipated reclamation expenses; title disputes or claims; and
limitations on insurance coverage. 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" or "be achieved".

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, including but not limited to risks
related to: the need for continued cooperation by the parties to the
proposed transactions in this negotiation and execution of definitive
agreement, and performance of their obligations thereunder; unexpected
events during construction, expansion and stasrt-up; variations in ore
grade, tonnes mined, crushed or milled; delay or failure to receive board
or government approvals; timing and availability of external financing on
acceptable terms; actual results of current exploration activities;
conclusions of economic evaluations; changes in project parameters as
plans continue to be refined; future prices of uranium and vanadium;
possible variations in ore reserves, grade or recovery rates; failure of
plant, equipment or processes to operate as anticipated; accidents,
labour disputes and other risks of the mining industry; delays in the
completion of development or construction activities, as well as those
factors discussed in or referred to under the heading "Risk Factors" in
Denison's Annual Information Form dated March 26, 2009 available at
http://www.sedar.com and its Form 40-F available at http://www.sec.gov.
Although management of Denison has attempted to identify important
factors that could cause actual results to differ materially from those
contained in forward-looking statements, there may be other factors that
cause results not to be as anticipated, estimated or intended.

There can be no assurance that such statements will prove to be accurate,
as actual results and future events could differ materially from those
anticipated in such statements. Accordingly, readers should not place
undue reliance on forward-looking statements. Denison does not undertake
to update any forward- looking statements that are incorporated by
reference herein, except in accordance with applicable securities laws.
Mineral resources, which are not mineral reserves, do not have
demonstrated economic viability. Readers should refer to the Annual
Information Form and the Annual Report on Form 40-F of Denison for the
year ended December 31, 2008 and other continuous disclosure documents
filed since December 31, 2008 available at http://www.sedar.com, for
further information relating to their mineral resources and mineral
reserves.

To view the Denison Mines Wheeler River Property Phoenix Uranium
Discovery Map associated with this press release, please visit the
following link: http://media3.marketwire.com/docs/DNN630map.jpg

Contacts:
Denison Mines Corp.
Ron Hochstein
President and Chief Executive Officer
(416) 979-1991 Extension 232

Denison Mines Corp.
James R. Anderson
Executive Vice President and Chief Financial Officer
(416) 979-1991 Extension 372

Denison Mines Corp.
James W. Gill
Chairman
(416) 979-1991 Extension 231

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