We report a rare case of primary endometrioid carcinoma of the ovary which presented clinically with rectal bleeding mimicking a rectal cancer. The patient's pre-operative evaluation included radiographic and sero-immunologic findings which indicated a primary ovarian neoplasm. Only two other cases of ovarian carcinoma with this presentation have been reported in the literature. Gynecologic processes that can present as bleeding gastrointestinal lesions are reviewed.