Mixed ovarian tumors are rare. The association of a granulosa tumor with a mucinous adenocarcinoma is exceptional and has never been reported to our knowledge in the literature. We report the case of a 44 year old patient, who consulted for an abdominal mass. The radiological explorations showed the presence of an enormous ovarian tumor, after hysterectomy the diagnosis of mixed ovarian tumor was made by histological and immunohistochemical study. The treatment is essentially surgical.