The incidence of cancer of the central nervous system (CNS) was established for the counties of Cork and Kerry using the Southern Tumour Registry data base. A total of 191 newly-diagnosed patients were identified over the five year period 1984-1988. This represents a crude annual incidence rate of 7.3 per 100,000 for males and 6.8 for females. When the incidence rates were adjusted using the accepted theoretical World Population, the annual rates were 6.7 and 6.4 for males and females respectively. These levels are higher than those reported for England and Wales (5.2 for males and 3.6 for females) and Scotland (5.9 for males and 4.2 for females). However the Irish rates are much lower than the most recent published statistics for Denmark which report rates of 12.9 for males and 11.8 for females. The risk of being affected by a CNS tumour increases substantially from 50 years onwards for a male and from 40 years on for females. The risk is seen to diminish for those aged 80 years or more. The most common locations of CNS tumours were the frontal, parietal and temporal lobes. Gliomas were by far the most common type of tumour.