A 51-year-old woman was hospitalized with constipation and bloody feces. Under diagnosis of a primary rectal cancer with peritonitis, an ileostomy was scheduled. Since peritoneal dissemination was found, histologically she was diagnosed as metastatic rectal cancer from serous adenocarcinoma of the ovary. Chemotherapy with paclitaxel and carboplatin was performed, and complete disappearance on assessable examination was seen. Eight months after the first operation, she underwent total hysterectomy, oophorectomy and low anterior resection of rectum. No viable cancer tissue could be found. After the second operation, she has been doing well without any recurrence for 1 year and half.