OBJECTIVE: To present the long-term results of ileum interposition in the ureter for uni- or bilateral ureteral obstruction. PATIENTS AND METHODS: Between 1981 and 2000, a total of 22 patients received an ileal segment interposition as a substitution for the ureter, of whom 18 were available for analysis. The mean age was 54 years (range 29-73). Patients were followed for a mean period of 65 months (range 2-196). Assessment included clinical examination, serum creatinine levels, renal ultrasonography, intravenous pyelography and isotopic renography. In eight patients, the ileal-ureteral substitution was the first reconstructive procedure. The other patients underwent up to four previous reconstructions of different types. Fourteen patients were treated for unilateral ureteral obstruction, four of whom had a functional or anatomical solitary kidney, the other four patients had bilateral obstruction. RESULTS: In 16 patients renal function improved after ileal-ureteral substitution. One patient underwent a nephrectomy because of a decreased renal function due to an obstruction at the level of the uretero-ileal anastomosis. One patient had a nephrectomy because of recurrent macroscopic hematuria caused by multiple arterio-venous malformations. Overall, 15 patients (83%) had a good functioning kidney after a mean period of 65 months. In three patients an early reintervention was necessary because of bleeding, small bowel obstruction and urinary leakage from a pyelo-ileal anastomosis. Six patients required a reintervention in the long-term: two had a nephrectomy, three had a re-anastomosis between the renal pelvis and the proximal ileal segment, while the sixth patient underwent a PNL for a kidney stone. Recurrent urinary tract infections were seen in six patients, of whom three had to undergo a reintervention. Metabolic acidosis was detected in two patients and was treated with sodium bicarbonate substitution. CONCLUSION: Ileal-ureteral substitution is a valuable procedure with good long-term results and an acceptable rate of secondary interventions in patients for whom other alternatives are not feasible.