OBJECTIVES: Duplication of the ureter and renal pelvis is the most common upper urinary tract anomaly in childhood. The anatomical and functional divisions between upper and lower moieties of duplex kidney are extremely variable. The underlying pathological condition associated with a lower moiety is usually massive vesicoureteral reflux (VUR) to the lower collecting system and only rare obstruction. The non-functioning upper moiety is usually associated with obstructive ectopic ureter (with or without ureterocele). Most lower pole heminephrectomies are carried out for non-functioning lower moieties. In most cases, the lower defunctionalised segment of the ureter is left in situ. Complete ureterectomy is usually performed if presence of VUR into the lower end of the corresponding ureter is shown. There is little information on the long-term outcome of residual ureteral 'stumps'. The purpose of our study was to review the long-term outcome of retained ureteral stumps in children undergoing heminephrectomy for non-functioning lower pole moieties in duplex kidneys. MATERIALS AND METHODS: The medical records of 19 patients who underwent 20 lower pole heminephrectomies for a non-functioning lower pole moiety of a duplex kidney between January 1990 and December 2000 were reviewed retrospectively. Median age at heminephrectomy was 4.5 years (range: 1 month to 12 years). Indications for heminephrectomy in the 20 renal units was reflux nephropathy in 16 (80%) and obstructive nephropathy in 4 (20%). All corresponding ureters were taken down as low as possible and transfixed through the heminephrectomy incision. Median follow-up was 8.5 years (range: 1-11 years). RESULTS: Eight (40%) showed VUR into the stump after lower pole heminephrectomy. Two of these underwent subureteral endoscopic correction of VUR with polytetrafluoroethylene paste and resection of the stump was carried out in remaining two patients for recurrent urinary tract infections (UTI). Remaining four of the eight patients demonstrated spontaneous resolution of VUR during follow-up. CONCLUSIONS: Our data suggest that the vast majority of patients with residual ureteral stumps after lower pole heminephrectomy do not require stump resection at long-term follow-up.