Mature teratoma is the most common germ cell tumor of the ovary. The tumor is essentially a benign neoplasm and surgical resection of the tumor is the treatment of choice. Recurrence with colorectal involvement after surgical removal of the primary lesion is exceedingly rare and has not been reported in Korea. We present a 43-year-old patient with a rectal mass who had already undergone left oophorectomy due to mature cystic teratoma and right oophorectomy due to hemorrhagic corpus luteum. The rectal mass was composed of a mature teratoma tissue. We postulate that leakage of the tumor elements from the cyst wall led to peritoneal tumor implantation and invasion to the rectal wall.