In twenty-seven patients who survived for six months or longer following renal homotransplantation, osseous changes developed in ten patients. Nine demonstrated aseptic necrosis of the femoral head, five had involvement of the hips alone, five showed aseptic necrosis at the knee joint, and two had aseptic necrosis of the humeral heads. The average time after transplantation when symptoms arose was seven months and the roentgen changes usually were seen two months later. The etiological explanation based on fatty embolization is theoretically satisfactory but unproved.