The incidence of primary intracranial tumours in a well defined population of persons older than 70 years (elderly) who resided in Kumamoto prefecture was examined. During the period from 1989 to 1995, primary intracranial tumours were diagnosed in 271 elderly people; of these, 155 (57.2%) tumours were confirmed microscopically. In a mean population of 216,000 people over the age of 70 years, this yields an average annual incidence rate of 18.1 cases/100,000 population/year. The incidence was lower in men (15.2/100,000 population) than women (20.3/100,000 population). The age specific incidence/100,000/year was 23.2 for the 70-74 year age group, 18.1 for the 75-79 year age group, 15.1 for the 80-84 year age group, and 7.6 for persons older than 85 years. The most common tumours were meningiomas (50.6%), followed by malignant gliomas (13.3%), pituitary adenomas (12.9%), schwannomas (6.6%), malignant lymphomas (3.7%), and benign astrocytomas (3.7%).