A retrospective study of primary intracranial tumors found in 19.760 consecutive autopsies and 72.972 consecutive biopsies during a period of over 41 years was carried out. Two hundred and five neoplasms comprising 69,7% of the primary intracranial tumors were located in the supratentorial compartment whereas 84 tumors (28,6%) were infratentorial in site. Gliomas constituted the largest group of primary tumors comprising 60,9% of the intracranial primary neoplasms. Most of gliomas were found in the cerebral hemispheres, particularly in the frontal lobes. Of the total number of gliomas 40,2% were astrocytomas, 29,6% glioblastomas, 10,6% ependymomas, 10,1% medulloblastomas, 5% oligodendrogliomas and 2,2% choroid plexus papillomas. Meningiomas constituted the second most common primary intracranial tumors being found in 56 cases (19%), most of them in parasagittal region, sphenoid ridge and anterior fossa. In the sella region there were 39 neoplasms including 21 pituitary adenomas, seven meningiomas, five craniopharyngiomas, four epidermoid cysts and two teratomas. Six capillary hemangioblastomas of the cerebellum and two chordomas of the clivus were also found. Sixty-five tumors occurred in patients under 15 years of age, 53,3% of them infratentorial in location--36% in the cerebellum, 9,3% in the brainstem and 8% in the fourth ventricle. The majority of these tumors were astrocytomas, medulloblastomas and ependymomas. The present data are discussed in relation to other pathological series found in the literature.