Open reduction and internal fixation was performed on 50 displaced acetabular fractures in 49 patients by nine different attending surgeons over a 10-year period. At an average follow-up of 38 months, poor results were noted clinically in 38% and radiographically in 40%. The incidence of short- and long-term complications was greater than in other studies. Particularly distressing was the 58% incidence of heterotopic ossification (HO). Twenty-four percent had grade III or IV; five hips were autofused and the remainder had 40-60% loss of motion. There was no correlation of HO with age, sex, fracture type, degree of comminution, associated femoral head fracture or dislocation, delay to surgery, or operative time. However, 26 of 28 patients who had a trochanteric osteotomy as part of the operative exposure developed HO. Other complications included wound infection (12%), avascular necrosis of the femoral head (10%), nerve palsy (8%), and deep vein thrombosis/pulmonary embolism (8%). The data suggest formulation of specific treatment protocols, an awareness of surgical risks, and that staff specialization may reduce complications and improve outcome. Avoiding a trochanteric osteotomy at surgery and using prophylactic postoperative irradiation or indomethacin are suggested to reduce HO.