OBJECTIVE To perform pyeloplasty as described by Andrson, Hynes and Küss by laparoscopic surgery for the treatment of ureteropelvic junction syndrome (UPJS): METHODS In patients with an indication for treatment for UPJS, we proposed laparoscopic pyeloplasty via a trans-abdominoretroperitoneal incision. The ureteroplevic junctions were exposed after detachment of the colon and were resected. Three Vicryl 4/0 running sutures were performed : two for the ureteropelvic anastomosis and one for the pelvic racket handle. The lower pole vessels were transposed posteriorly to the urinary tract and all anastomoses were protected by a previously inserted stent. Operating times and postoperative hospital stays, and volume of blood loss were recorded. At three months, five patients are evaluable clinically and radiologically by comparison of pre- and postoperative urographies. RESULTS From May 1994 to May 1995, seven consecutive patients (mean age : 33.4 years, range : 17-65 years) presented with symptomatic congenital UPJS. Three patients had a lower pole artery crossing the anterior surface of the junction, and two had a giant renal pelvis. The mean operating time was 120 minutes (max : 147 min; min. : 90 min). The blood loss was always less than 50 ml. The mean hospital stay in the absence of complications (1 case) was three days (max. : 4 days, min. : 1.5 days). This one complication was due to a postoperative fistula resulting from a technical error requiring an additional fortnight in hospital. The five evaluable patients are asymptomatic. Radiological results showed frank improvement in four out of five cases, while the dynamic appearance was improved in the other case. CONCLUSIONS UPJS can be treated by laparoscopic surgery according to proven surgical principles, provided it is performed in a perfectly equipped operating room, by a surgeon and operating team experienced in this type of surgery. Laparoscopic pyeloplasty therefore constitutes an alternative to open surgery and endopyelotomy, as the patients benefit from the advantages of laparoscopic surgery without impairing the efficacy of treatment of UPJS.