Acetabular fractures assume great clinical importance because acetabular is weight bearing joint in the lower extremity. The undisplaced fractures of the acetabulum gave satisfactory results with closed method, but the treatment of displaced fractures have been controversial. A clinical analysis was performed on the 72 patients with displaced acetabular fractures, who had been treated at Soonchunhyang University Hospital from January 1980 to December 1989. The results obtained were as follows. 1. The prevalent age ranged from 21 to 50 years, which comprised 86.1% of all, and the ratio between male and female was 3:l. 2. The most common cause of injury was traffic accident, which comprised 76.4%. 3. According to Letournel's classification, simple fracture was 38 cases (52.8%), associated fracture was 34 cases (47.2%) and hip dislocation was associated in 28 cases (38.9%) and most common was posterior (20.8%). 4. Closed treatment was done in 47 cases and open treatment in 25 cases. 5. Results of open treatment group were better than closed treatment group in both clinical and roentgenographic study. 6. The complication were occured in 14 (29.8%) out of 47 cases of closed treatment group, and 10 (40.0%) out of 25 cases of open treatment group. 7. Not only choice of treatment but also determination of surgical approach require accurate assessment of the fracture pattern in this region of complex bony architecture by careful radilogic analysis.