Pyelouretersotomy or ureteroureterostomy was the urinary tract reconstructive procedure in 114 of 132 consecutive renal transplants performed at the Massachusetts General Hospital from September 1967 to December 1973. Anastomotic leakage was the only complication related to failure of pyeloureterostomy or ureteroureterostomy. This occurred in nine transplants (7.9%). Since 1970, only four anastomotic leaks have occurred in 79 consecutive pyeloureterostomies or ureteroureterostomies. Six of the nine primary anastomotic leaks were corrected either by retrograde ureteral catheter drainage or re-suturing of the anastomotic defect. Only one patient died as a result of complications following a leak. The operative technique is described with emphasis on the important details believed necessary for consistent success in performing this procedure.