This is a retrospective review of 24 patients with late-onset Perthes disease treated with shelf acetabuloplasty. The mean age of the patients was 9.8 years. The medial joint space ratio improved from 1.66 to 1.47 (P<0.05) and the acetabular cover ratio improved from 0.87 to 1.18 (P<0.001). At maturity, five hips were Stulberg II, 13 were Stulberg III and six were Stulberg IV. The study suggests that shelf acetabuloplasty favourably affects long-term Stulberg grading and therefore outcome compared with historic nonoperative treatment regimens. We believe that the procedure deserves further evaluation in any future randomized-controlled trial of the management of late-onset Perthes disease.