The Minnesota Heart Survey (MHS) is among the few population-based longitudinal studies to monitor and explain trends in coronary heart disease (CHD) mortality and morbidity, the leading cause of death and disability in the United States. It encompasses a large and well-defined community, the Minneapolis/St. Paul (Twin Cities) metropolitan area of Minnesota, comprising a population of 2.3 million (1990 census) For almost two decade the Minnesota Heart Survey has made contributions to understanding 1) the components of the decline of coronary heart disease mortality including incidence rate, hospitalized attach rate, case fatality, and population levels of CHD risk factors; and 2) the methodology of disease surveillance in a time when classification and diagnostic technologies are constantly changing.