The North Karelia Project - a community-wide health intervention programme - was launched in 1972 as response to the local petition to reduce the heavy toll of heart disease in North Karelia. The strategy of community-based prevention was based on the previous pioneering international work on epidemiology of cardiovascular diseases and prevention in which Finland had in many ways participated. Comprehensive scientific evaluation of the programme was carefully designed. The effects of the programme on risk factor reduction and on prevention of cardiovascular diseases are assessed by large population surveys every five years and by data on incidence of cardiovascular diseases and mortality rates. The authors present the 15 years' results and some of the most recent findings of the North Karelia Project, and discuss the overall experience and its national an international implications.