Over 21,000 hospital episodes due to cerebrovascular disease (CVD, ICD-8 nos. 430-438) were registered in the Helsinki hospitals in 1970-1980. Of those 17,629 were identified as new cases. The age-adjusted incidence of haemorrhagic and thrombotic stroke (430-433) declined during the period 1970-1975 from 221 to 139 cases/100,000 inhabitants, whereafter no further decrease was observed. The decline in incidence was significant in both sexes. Analysis by diagnosis group showed that the decrease was confined to the incidence of haemorrhagic stroke (430-432), whereas the incidence of thromboembolic stroke (433, 434) and transient ischaemic attacks (435) remained virtually unchanged. Survival was mainly determined by patient age and type of CVD. Intracerebral haemorrhage and occlusion of precerebral arteries exhibited the poorest short-term prognosis. About half of the patients hospitalised due to cerebral thrombosis and embolism survived over one year. Long-term prognosis of the major CVD groups was very poor with only 10% of the patients alive after eight years. Transient cerebral ischaemia and subarachnoid haemorrhage had a clearly better prognosis, the survival rates after eight years being 45 and 30%, respectively.