Exhibit 4

Ontario
Securities
Commission Commission des
valeurs mobilières
de I ’Ontario P.O. Box 55, 19th Floor
20 Queen Street West
Toronto ON M5H 3S8 CP 55, 19e étage
20, rue queen ouest
Toronto ON M5H 3S8

RECEIPT

Denison Mines Corp.

This is the receipt of the Ontario Securities Commission for the Preliminary Short Form Prospectus of the above Issuer dated December 9, 2010 (the preliminary prospectus).

The preliminary prospectus has been filed under Multilateral Instrument 11-102 Passport System in British Columbia, Alberta and Nova Scotia. A receipt for the preliminary prospectus is deemed to be issued by the regulator in each of those jurisdictions, if the conditions of the Instrument have been satisfied.

December 9, 2010

Leslie Byberg Leslie Byberg

Director, Corporate Finance

SEDAR Project # 1674373