Ureteral complications occurred in 23 cases after 225 renal transplantations. The complications consisted of 17 urinary fistulas and 6 stenoses of the ureter. Fourteen of the urinary fistulas were successfully treated by conservative management. Two transplants were lost secondary to operation because of ureteral obstruction. Factors contributing to ureteral leakage were the technique of ureteral anastomosis, the handling of the donor ureter during donor nephrectomy and possibly ureteral necrosis by rejection crises. Ureteral stenosis and rejection crisis may have the same symptoms. Urinary fistulas can easily be observed by the urine extravasation. The treatment of urinary fistulas can be managed only by replacing the suprapubical drainage. The stenosis of ureter with subsequent deterioration of graft function needs an operation with the danger of loss of the transplanted kidney.