Osteonecrosis occurred in nine of thirty-six children following renal transplantation. The distal femoral condyle was the most common location but the femoral head was the most symptomatic and required total hip replacement in three of five patients. Total steroid dosage did not correlate with the development of osteonecrosis. There were no cases of osteonecrosis in patients under the skeletal age of ten years or in patients who did not have rejection reactions. In three children non-progressive focal lesions developed, similar to those of osteochondritis dissecans.