Ovarian teratoma is a common neoplasm among women in their reproductive age
. On the contrary, testicular teratoma is a rare tumor.(1,2) It usually app
ears during infancy as a palpable scrotal mass. We report a case of mature
teratoma of the right undescended testis diagnosed on the basis of prenatal
ultrasonography. The ultrasonographic diagnostic features and clinical imp
ortance will be discussed.