The incidence rate for primary intracranial tumors in the Province of Trento (Italy) from 1977 to 1984, adjusted to the Italian population, is 8.5/100,000/year (8.0 for males and 9.1 for females). The age-specific distribution is nearly the same as that reported in other studies. It is bimodal with a mild increase until the ages of 40-44 years followed by a peak reaching a maximum at the ages of 55-64 years and then declining. The commonest tumors in males were glioblastomas (m/f ratio = 1.3) and in females meningiomas (m/f = 0.4). Pituitary adenomas were 15.3% of all tumors with a m/f ratio of 0.6. Factors causing discrepancies between the rates reported by various authors are discussed.