A 31-year-old female had been diagnosed with endometriosis in 1996 and received hormone therapy for endometriosis, which was effective, but she began to notice pain on defecation and left back pain during menstruation in 1997. In December 1998, she entered our hospital and laparoscopic ovarian cyst excision was performed. The rectum, sigmoid colon, and left ovary were densely adherent and also strongly stuck to the Douglas pouch. After the operation, endometriosis of the rectum was diagnosed by colonoscopy and barium enema. Another operation was thought to be required because rectal stenosis was severe, but an operation at this point was predicted to be difficult, so preoperative hormone therapy with LH-RH analog (leuprorelin acetate, 3.75mg/month) was given for 5 months first. After hormone therapy, the patient did not complain of pain on defecation, but there was still a possibility of recurrence. On July 1, 1999, low anterior resection with partial left uretectomy was performed. Exploration of the peritoneal cavity showed improvement of pelvic adhesion that demonstrated a significant effect of preoperative hormone therapy.