Gossypiboma refers to a mass usually made of cotton (e.g., surgical gauze or sponge) that is accidentally left in a patient’s body during surgery. We report the case of a 54-year-old multigravida menopausal woman who previously underwent cesarean section to deliver her second child. She was referred to our medical center after a 7 cm right ovarian mass with malignant potential was discovered. A diagnostic laparotomy was performed then confirmed the presence of a 10 cm gossypiboma attached to a metallic ring. This case is an alarming example highlighting the importance of adequate intraoperative counting of gauze and radiologic evaluation of chronic pelvic pain.