Over a four-year period, twenty-four patients who had a complex fracture of the acetabulum were treated by the same surgeon. The operation consisted of open reduction and internal fixation with combined anterior and posterior exposures during the same period of anesthesia. The cases of these patients were reviewed to ascertain whether access to both acetabular columns during the same procedure facilitates open reduction and internal fixation and to determine the indications for this combined procedure. As determined by intraoperative assessment and at follow-up examination four to thirty-two months postoperatively, anatomical reduction and rigid fixation were achieved in 88 per cent of the patients. No patient had an infection of the wound. All twenty-four patients had some degree of heterotopic ossification; as defined by Brooker et al., it was Class I in seven, Class II in thirteen, Class III in three, and Class IV in one. However, the heterotopic ossification limited motion of the hip enough to impair function in only two patients. We concluded that combined anterior and posterior exposures facilitate reduction and fixation and that these approaches should be used during the same period of anesthesia whenever anatomical reduction and rigid internal fixation cannot be achieved through a single exposure. Heterotopic ossification should be expected postoperatively, but it is rarely clinically important, at least in the short term.