Purpose: We assessed the role and long-term outcome of lower pole heminephrectomy in the treatment of nonfunctioning lower renal moieties in children with duplex kidneys. Materials and Methods: Between 1979 and 1994, 54 lower pole heminephrectomies were performed in 53 patients 1 to 192 months old (mean age 54) with duplex systems. A total of 15 patients was prenatally diagnosed, while the others presented with a urinary tract infection (36), orchiepididymitis (1) and failure to thrive (1). The surgical technique was essentially similar to that of upper pole heminephrectomy. Results: Operative course was uneventful except for intraoperative bleeding in 5 cases, which necessitated blood transfusion, and a postoperative urinary tract infection in 1. Followup ranged from 3 to 168 months (mean 56.9). Postoperative renograms available in 34 cases showed unchanged differential function in 12 and an ipsilateral 2 to 14% decrease (mean 5.65%) in 22. No late complications were detected except in 1 patient, who had postoperative urinary tract infections and subsequently underwent removal of the ureteral stump. Our series includes 4 patients with solitary ipsilateral upper poles (after the contralateral kidney was removed or nonfunctioning) who had good renal function at long-term followup despite the reduced parenchymal mass. Conclusions: Based on our experience it seems that lower pole heminephrectomy is the treatment of choice in cases of nonfunctioning dilated lower segments of duplicated kidneys.