Urologic complications occurred in 13.2% of the 718 patients who received renal transplants performed during a 26-year period at the Peter Bent Brigham Hospital. The complication rate remained constant over the quarter century period, whereas the rate of death caused by complications decreased significantly during the last decade. This was due, in part, to recent use of ultrasound techniques permitting earlier recognition of complications. The majority of urologic complications occurred during the first month after transplantation. Contributing factors included technical problems, ischemia, and perhaps allograft rejection. No correlation could be found between degree of HLA match or mismatch and likelihood of complication. Internal indwelling stents offered substantial advantages over nephrostomy tubes for temporary urinary diversion. The most serious complications encountered were calyceal-cutaneous fistulas associated with donor kidneys with multiple renal arteries. "Bench" operation has proved to be a major technical advance in the prevention of these fistulas.