Seventy cases of histologically verified intracranial germ cell tumor were reviewed: 43 germinomas, 16 immature teratomas, seven mature teratomas, two embryonal carcinomas, one choriocarcinoma, and one yolk sac tumor. The male-to-female ratio was 2.6:1. The average age was 19 years in patients with germinoma, 11 years in patients with immature teratoma, and 17 years in patients with mature teratoma. Duration of symptoms averaged 19 months for germinoma, three months for immature teratoma, and 11 months for mature teratoma. Sixty-six lesions were located in the midline. Fifty-eight percent of the germinomas arose anterior to the pineal gland, whereas 29% of the immature and 14% of the mature teratomas were located anteriorly. The histologic appearance of the germinomas was indistinguishable from that of the usual testicular seminoma. The immature teratomas contained tissue from all three germ layers and exhibited morphologic features of fetal tissue. Of 14 immature teratomas, seven contained, in addition, foci of other malignant germ cell elements; thus, there were two teratocarcinomas, two lesions with germinoma and immature teratoma, two lesions with extensive rhabdomyoblastic differentiation in an immature teratoma, and one lesion with both germinoma and embryonal carcinoma in addition to immature teratoma. The seven mature teratomas consisted of fully differentiated epithelial and mesenchymal tissues. In 23 cases, immunoperoxidase stains for human chorionic gonadotropin (HCG), alpha-fetoprotein (AFP), and carcino-embryonic antigen (CEA) revealed patterns which, with minor exceptions, were essentially identical to those found in genital germ cell lesions. Survival was longest for patients with germinomas. In classifying germ cell tumors of the central nervous system, the World Health Organization's (WHO) classification of testicular germ cell tumors is preferable to its present classification of intracranial germ cell tumors.