PURPOSE: The purpose of this study was to review the clinical and radiographic results after plate fixation for displaced acetabular fracture. MATERIALS AND METHODS: A clinical analysis was performed on 47 cases of displaced unstable acetabular fracture which had been fixed with plates and screws. Clinical and radiographical results were analyzed according to Epstein criteria. RESULTS: In 44 cases, internal fixation was performed using only plate and screws. In three cases, the fixation was augmented with cerclage wiring. The fracture type included posterior wall or posterior column fracture in 37 cases(78.7%). Satisfactory results were achieved in 39 cases(86.7%) on clinical grade and 40 cases(88.9%) on radiographic grade. The complications were deep wound infection in two cases, avascular necrosis of femoral head in one case, post traumatic arthritis in 2 cases, and malunion with partial ankylosis in one case. Total hip arthroplasty were needed in two cases with avascular necrosis and infection. CONCLUSION: Early surgical treatment including accurate anatomical reduction and stable internal fixation is emphasized for better clinical and radiographic results. The plate and screw fixation is well indicated for posterior wall and/or posterior column fracture of acetabulum.