Incomplete transiliac osteotomy is commonly used in the surgical treatment of spastic hip disease in children with cerebral palsy. The osteotomy hinges through an intact sciatic notch and an open triradiate cartilage. We asked whether incomplete transiliac osteotomy, combined with varus osteotomy of the femur and soft tissue reconstruction, performed after skeletal maturity could improve hip coverage and acetabular shape and provide pain relief in patients with spastic hip disease. We retrospectively evaluated 27 consecutive adolescent patients (33 hips) with cerebral palsy in whom an incomplete transiliac osteotomy was performed after closure of the triradiate cartilage. The mean age at surgery was 15 years. Five hips were dislocated and 28 hips were subluxated preoperatively. The minimum followup was 2 years (mean, 3.3 years; range, 2 years-7.5 years). The subluxated hips had a minimum Reimers' migration index of 23% (mean, 52%; range, 23-95%), which was reduced to 0% (mean, 7%; range, 0-39%) at followup. The minimum preoperative Sharp's angle was 34 degrees (mean, 52 degrees ; range, 34 degrees -70 degrees ), which was reduced to 20 degrees (mean, 35 degrees ; range, 20 degrees -50 degrees ) at followup. A painless hip was achieved in 26 of 33 hips at followup. An incomplete transiliac osteotomy can be performed after skeletal maturity, resulting in a painless and stable hip in the majority of patients.