We report a case of ureteral endometriosis thought to have developed following relapse of pelvic peritoneal endometriosis after laparoscopic surgery. The patient was a woman in her late 40s who had undergone laparoscopic right adnexectomy for an endometrial cyst 5 years earlier. Electrocoagulation was performed for residual endometriosis of adherent cyst wall on the right sacrouterine ligament. The normal left ovary was preserved and she received no postoperative hormonal therapy. She developed right back pain during menstruation 5 years after the surgery. Pyeloureterography revealed stenosis of the ureter to the right of the uterus. Urinary cytology revealed endometrial cells with no atypia. Conservative management was opted for because malignant transformation of endometriosis was considered unlikely and she was expected to reach menopause within a few years. She is now doing well 24 months after initiation of progestin treatment with placement of a ureteral stent. Postoperative hormonal therapy is recommended for patients who are considered to have possible lesions of residual endometriosis and for whom ovarian function is preserved.