Background and Purpose Seasonal influence on the incidence of and mortality from cerebrovascular disease has been reported during the last three decades, but generally with some discrepancy in results, particularly regarding stroke subtypes. The aim of this study was to examine seasonal variation in the incidence, mortality, and case-fatality rate of stroke in data from the FINMONICA population-based stroke register. Methods During 1982 to 1992, 15 449 stroke events were registered in the monitored populations aged 25 to 99 years in three geographic areas of Finland: the provinces of Kuopio and North Karelia in eastern Finland and the Turku/Loimaa area in southwestern Finland. We analyzed the seasonal and monthly incidence, mortality, and case-fatality rate of stroke and subtypes of stroke by pooling the data for the three areas and stratifying by sex and age. Results The rate of occurrence of ischemic stroke events was 12% (95% confidence interval [CI], 5% to 20%) greater in men and 11% (95% CI, 4% to 19...