A 7-year-old girl was hospitalized with urinary incontinence. Intravenous pyelography showed the dilatation of upper segment of the right kidney, in which slight radioisotopic accumulation was detected on renal scintigraphy with 99mTc-DMSA. On computerized tomographic (CT) scan, a cystic mass shadow occupied the retroperitoneal space. During surgery, the right kidney was found to be completely duplicated and the ectopic ureter opened in Vestibule vaginae accompanied with midureteral stricture. The ectopic ureter was incised above the strictural site and anastomosed with the ureter of the lower segment. Although approximately 700 cases of ectopic ureter have been reported in Japan, congenital midureteral stricture accompanying ectopic ureter is extremely rare.