Teratocarcinoma is a form of mixed germ cell tumor composed of a mixture of teratoma and embryonal carcinoma. It is rarely found in the brain, but when present it is most commonly found in the pineal region. We investigated a case of primary teratocarcinoma in the pineal region. The patient was a 10 year old boy who had suffered from a bitemporal headache for one month. Brain CT and MRI revealed a rather well defined ovoid heterogenous mass in the pineal gland region, measuring 4.3 x 3.8 x 3.0 cm in size. Microscopically the tumor contained areas of immature teratoma and embryonal carcinoma. Immunohistochemical staining revealed positive reactions for cytokeratin, epithelial membrane antigen, carcinoembryonic antigen, and alpha-fetoprotein in the embryonal carcinoma component.