We present the case of a 45-year-old female patient who was admitted with a history of pelvic pain, constipation, and dysmenorrhea. CT scan and u/s images revealed cholelithiasis, benign nodular hyperplasia of segment IV of the liver and uterine fibromyoma. During laparotomy, firm adhesions between the posterior wall of the uterus and the rectum were found and the incisional biopsy reveals an undifferentiated adenocarcinoma. Then, total resection of the uterus was performed with en block resection of the adherent part of the rectum and part of the posterior wall of the vagina. The final histopathological report showed the presence of uterine fibromyoma, nodular hyperplasia of the liver and rectal endometriosis without any sign of malignancy. The patient after 5 years of follow up remains healthy. Rectal endometriosis represents an uncommon localization of pelvic endometriosis where the symptoms and clinical findings are non-specific making the definitive preoperative diagnosis difficult. Endometriosis should be included in the differential diagnosis of chronic pelvic pain in combination with defecation disorders in female patients of reproductive age.