This paper describes a new technique for greater trochanteric hip arthroplasty in which the femur is divided at the subtrochanteric level and the upper fragment rotated through 180 degrees to place the greater trochanter deeply in the acetabulum; with the lower limb in the weight-bearing position the fragments are then fixed with a short intramedullary nail. This operation was carried out in a boy aged 4 years 6 months in whom the femoral head and neck had been destroyed by septic arthritis. Ten years later leg-lengthening was performed. When reviewed at the age of 20, he had a stable hip, a satisfactory range of painless movement, and shortening of only 2.5 cm; he could walk and run for long distances with only a slight abductor lunch.