Avascular osteonecrosis has frequently occured in patients who have undergone transplantation of a kidney and generally has been considered to be a complication of the use of corticosteroids. But there are controversies regarding their dosage and duration of use in its influence on prevalence of avascular osteonecrosis. We analyzed the cases of our patients who underwent transplantation of a kidney and who we were able to follow up more than 8 months. l. Of a total of 300 patients, osteonecrosis developed in 24 joints of 12 patients. 2. Osteonecrosis was more frequently found in group of patients who were administered with larger doses of steroid. 3. Rejections of the transplanted kidney occured more frequently in those groups with osteonecrosis. 4. Most of rejections occured within 3 months after renal transplantation. 5. It took 4–26 months (average 12.3 months) the osteonecrosis could be found. 6. There were no differences in blood concentration of calcium phosphate and creatinine between osteonecrosis and non-osteonecrosis group. 7. Replacement arthroplasties were done in 10 joints without significant complication.