The choice of which decision to use for open reduction and internal fixation of complex acetabulum fractures depends on several variables. We report on 26 patients in whom a lateral extension of the ilioinguinal incision was used to achieve fracture reduction and stabilization. The lateral extension allowed visualization of the lateral ilium, in some cases passage of cerclage wires around the anterior and posterior columns, and in some cases placement of lateral to medial lag screws above the dome of the acetabulum. Reduction with a step of 1 mm or less and a gap of 3 mm or less with joint congruence was achieved in 21 patients (81 per cent). No patients had clinically significant heterotopic ossification. One patient had a transient postoperative femoral neuropathy, one a superficial infection, and one a deep infection. We recommend this lateral extension as an option during surgery of complex acetabular fractures through the ilioinguinal incision.