Background: Distal radius fracture is among the most common fractures of the long bones that are seen in all age groups. Presence of different treatment protocols explains the challenge and controversy in treatment. Methods: In a clinical trial study, on 100 patients with stable extra articular distal radius fractures, 50 cases were randomly treated with short and 50 with long arm casts in a one year period in three training hospitals in Mashhad-Iran. All the long casts were changed to short casts in the forth week and all the casts discontinued in the sixth week and the patients assessed for the elbow range of motion , forearm supination-pronation, :::union:::, mal:::union:::, the patient satisfaction, and distal radioulnar joint stability in the 6th and 18th weeks after treatment. Results: The severity of fractures in both groups was similar. We didn’t find any case of non:::union:::, unacceptable mal:::union:::, regional pain syndrome, carpal tunnel syndrome or compartment syndrome. All the patients with short arm cast were satisfied in contrast to the other group. Range of motion had been better saved in short arm cast and in younger patients. Conclusion: This study shows that the effectiveness of short arm cast is the same as long arm cast the complications are fewer than long arm cast, and the patient's satisfaction is better in short arm cast. So, we suggest closed reduction and short arm cast for the treatment of stable extraarticular A2 type of OTA distal radius fractures.