PURPOSE: The purpose of this study was to clinically evaluate the series of displaced acetabular fractures and also to verify that the accuracy of reduction is one of the important prognostic factors for good clinical outcome. MATERIAL AND METHODS: The study is based on retrospective review on 23 patients with displaced acetabular fractures who had undertaken open reduction and internal fixation during the period of June 1st, 1994 to December 31st, 1997. Follow up evaluation of the patients was done for average 25.1 months(15-45 months). According to Letournel and Judet classification, 15 of 23 hips hips were classified as elementary types and 8 hips as complex types. Average age at operation was 43.4(22-66years) years old. Twenty one of 23 fractures were caused by traffic accidents. Twenty of 23 hips were combined with hip dislocation, 18 of which were posterior type. Twenty-one of 23 hips were operated on by single operative approach (Kocher-Langenbeck or iliofemoral approach), while 2 cases were approached by anterior and posterior approach in one stage. Functional evaluations and Radiographic evaluations for the postoperative status of 34 patients were done with the criteria by Matta. RESULTS: Overall clinical results for 14(60.9%) hips of total 23 hips were excellent or good. According to radiographic criteria, 13(56.5%) hips were classified as excellent or good. Postoperative hip joint congruity was found in 13(56.5%) hips, 11(84.6%) of which were included in good or excellent categories of clinical as well as radiographic results. CONCLUSION: These findings indicated that for most displaced acetabular fractures, the good results with patient satisfaction can be achieved, if the hip joint were congruous post-operatively. Therefore the accuracy of reduction was verified as very important prognostic factor for good clinical and radiographic results.