Fifty eight patients who underwent ileal conduit formation in our hospital for the past 14 years were reviewed. Out of them, 11 patients developed hydronephrosis which should be treated. It occurred due to urolithiasis, recurrent tumor, contracted ileal loop in one patient respectively, and ureteroileal junction stricture in 8 patients (10 ureteral units). The 8 patients consisted of 6 males and 2 females. All of the males underwent total cystectomy because of bladder tumor (T.C.C.), and the females had anterior pelvic exenteration because of uterine cancer (adenocarcinoma). Out of 10 ureteral units, 7 were corrected by surgical intervention, 1 was dilated with endourological procedure, and 2 had no treatment. Six ureteral units including 1 ureteral unit treated by an endourological method resulted in improvement or disappearance of hydronephrosis. Histological examination of the stricture revealed fibrosis in 7 ureteral units treated surgically. According to our clinical studies, infection in the pelvic space seemed to be one of the causes which brought about ureteroileal junction stricture.