Gonodoblastomas with ovarian germ cell tumors other than dysgerminoma coexists very rarely with yolk sac tumor (YST). Because of this rarity, we report a case of gonadoblastoma with YST. An 18-year-old female patient was admitted to our hospital with an abdomino-pelvic mass. Ultrasonographical examinations revealed a 15X14 cm heterogenous pelvic mass with calcific foci in the left adnexal area. Macroscopically, the resected mass was oval and measured 18X15X15 cm and weighed 3150 gm. Histological examination showed both gonadoblastic and YST areas. There were many gonadoblastic nests in the subcapsular areas of the tumor. The gonadoblastic nests were composed of large and small cells. The YST areas showed enteric differentiation and numerous hyaline globules. Immunohistochemical examination may help in the diagnosis of these gonadoblastoma with YST.