Sixty six Colles' fracture were treated with radial slab or U-cast (sugar tong splint), from January 1982 through May 1984 at the Department of Orthopaedic Surgery of St. Mary Hospital. A prospective study was made and was evaluated under the subjective criteria of Gartland and Werley, and the objective criteria of Scheck. The results of this study were as follows: 1. All of 66 cases was closed fracture and the incidence was high in females who aged over 6thdecades. 2. In 43 cases of stable fracture, 18 (94.7 %) out of 19 cases treated with radial slab and 21 (87.5%) out of 24 cases treated with U-cast showed satisfactory result. 3. In 23 cases of unstable fracture, 6 (54.6%) out of 11 cases treated with radial slab and 9 (75%) out of 12 cases treated with U-cast showed satisfatory result. 4. As a result, we found that the result of the treatment with radial slab was superior to the U-cast for the stable Colles fracture, however, all of two methods were not staisfatory for the unstable Colles fracture although the U-cast group showed better result.