The treatment of acetabular fractures is composed of operative and conservative methods, however, they are still controversial. Generally, because the acetabular fracture involves the joint surface and one sequalae such as post-traumatic arthritis can follow treatment, therefore an accurate reduction and postoperative early mobilization to obtain the prevenation of joint stiffness and arthritis are required. In order to achieve these purposes, we have studied and done a comparative survey between conservative and operative treatment on 55 patients with acetabular fractures, who were treated at our department from Jan. 1982 to Dec. 1988. Results were obtained as follows. 1. The prevalent age was the third decade and the cause of injury was traffic accidents in the majority. 2. The most common type of fracture was a posterior wall by Letournel classification. 3. Satisfactory results of operative treatment were 76% and conservative treatment 47%. 4. The complications were post-traumatic arthritis, ectopic ossification, peroneal nerve palsy and skin infection. 5. In the majority of displaced acetabular fractures, ORIF was recommended.