Two groups of patients underwent renal transplantation and were managed similarly in all respects, except for the dosage of corticosteroids administered post-operatively. For the first group, sixty-eight in number, the dosage was approximately three times greater than that for the second group with 136 patients. Avascular necrosis of bone appeared in sixteen patients in the first group and in two in the second. A greatly increased incidece of avascular necrosis after repeated transplantations was noted.