From 1977 to 1983, 17 patients with 20 longstanding congenitally dislocated hips were treated with a one-stage combined operation and then followed for more than 3 years by our institution. The growth of the proximal femur after femoral osteotomy was studied. The average neck-shaft angle was 111° immediately after operation, and 128° at follow-up. The outcome was largely independent of either age at operation or bilateral involvement. Our findings revealed 30% good and 50% excellent results in our patients.