Purpose: To report our experience with transperitoneal laparoscopic pyeloureterostomy for duplication of the collecting system. Patients and Methods: Since January 2003, two adult patients with incomplete duplication of ureter with ureteropelvic junction obstruction of the lower moiety and a 4-month-old male baby with complete duplication of the ureter with reflux in the lower moiety underwent transperitoneal laparoscopic pyeloureterostomy. The baby also had excision of the lower-moiety ureter. Results: There was no significant intraoperative or postoperative morbidity. Follow-up imaging revealed good drainage. Conclusion: With increasing experience in laparoscopic reconstructive urologic procedures, laparoscopic pyeloureterostomy is a feasible option, even in infants.