RESUMO
Ovarian teratomas are the most common germ cell neoplasm. They include mature cystic teratomas, monodermal teratomas (neural tumors, struma ovarii, carcinoid tumors) and immature teratomas. Malignant transformation of mature teratoma is very rare event and a case of sequence occurance of mature teratoma and immature teratoma in same patient is not reported yet in Korea. A 17-year-old female was found to have a huge mature teratoma of the right ovary 3 years ago. That was treated with surgery. Three years later, Immature teratoma was discovered in left ovary and treated with surgery followed by chemotherapy. We experienced one case of sequent occurrence of mature teratoma and immature teratoma on both ovary in same patient. We present it with a brief of literature.