We report a case of retroperitoneal endometriosis involving the periureteral tissues of the left ureter. The patient suffered from cyclical symptoms of left ureteral obstruction during menstruation. Endometriosis of the ureter is not common and in this case the preoperative diagnosis presented difficulties due to the absence of any pathological findings during the clinicolaboratory evaluation of the patient before or after menstruation. The patient was managed with surgical resection of the affected ureteral segment and subsequent end-to-end anastomosis of the left ureter. A brief review of the subject is also presented.