In women, adnexal mass is a common gynecologic problem. Serous cystadenoma is a benign ovarian tumor which is seen in gynecological pathologies, especially in the reproductive period. Serous cystadenoma is usually detected during the gynecological examination and sometimes as a mass in the abdomen. Benign ovarian tumors can rarely present as giant masses of the abdomen. Surgical exploration and resection are recommended for the treatment of benign ovarian tumors. The aim of this case report is to present a 39 years old female patient with a giant abdominal mass, who underwent surgery.