Objective: To evaluate the results of operative treatment of complex fractures of the acetabulum. Material and methods: For the period 1992 Ð 2001 þfty one patients with complex acetabular fractures were treated surgically and followed up for an average 4 years 3 months (range, 1 Ð 11 years). There were 34 males and 17 females of an average age of 39 years (range, 18 Ð 64 years). Thirty one of the patients sustained multiple trauma. The mean operation time was 9 days (range, 3 Ð 22 days). According to Judet-Letournel classiþcation there were 2 posterior clolumn/posterior wall fractures, 10 Ð transversal/posterior wall, 7 Ð T-type, 9 Ð T-type/posterior wall, 11 Ð anterior column/posterior hemitransversal and 12 Ð both column injuries. Posterior Koher-Langenbeck, ilioinguinal, extended iliofemoral or combined approaches were used depending of fracture pattern. Internal þxation was done with lag column screws, column shaped plates, brim plates or buttress plates. Spring plating with stright or T plates was widely used in cases of comminution. Ealy weight-protected motion was conducted after surgery. Results: Average operative time was 3.5 h (range 1.5 Ð 8 h), and average blood loss was 1200 ml (range 450 Ð 2300 ml). According to Mattañs criteria anatomical reduction was achieved in 23 cases, good Ð in 13, fair Ð in 11 and poor Ð in 4. Late outcome was evaluated according to Merl dñAubigne-Postel-Matta scale. Nineteen ecxellent, 16 good, 11 fair and 5 poor results were recorded. The last were due to arthritis, avascular necrosis or chondrolysis. The late results correlated strongly with quality of reduction and initial cartilage damage. Early complications were 1 case of operative bleeding, 1 intraarticular screw penetration, 5 jatrogenic nerve palsies (2 of femoral cutaneus nerve and 3 of peroneal nerve) and 1 superþcial inection. Late complications were 1 case of chondrolysis, 2 avascular necroses and 2 Grade III heterotopic ossiþcations. Conclusion: ORIF provides high prevalance of excellent and good results in complex acetabular fractures and should be considered as a method of choice. The quality of reduction is of most importance for þnal outcome. Initial cartilage condition, fracture type and degree of comminution should also be taken in mind for late prognosis. As the surgery is demanding perfect surgical skills, special experience and adequate equipment are required for þnal success.