Avascular necrosis of bone is a serious complication associated with steroid therapy in high dose. Ninetynine patients with functioning renal allografts transplanted 1964-1973 and subjected to steroid therapy were examined with regard to this complication. Osteonecrosis developed in 8 patients afflicting 13 joints. The process was localized to the femoral head, the condyles of the femur, tibia and the head of the humerus. The symptoms became manifest 7-33 months after the first transplantation. The severity of the disorder in 3 patients did not allow rehabilitation by conservative means. The roentgenographic, scintigraphic and clinical findings are described and the orthopaedic treatment discussed.