The study is conducted on defined populations of Indians living on reservations and involves two components: a review of death certificates and health care records: and a population survey of the prevalence of and risk factors for cardiovascular disease. The population survey phase consists of three examinations for cardiovascular disease risk factors, clinical cardiac disease, and the use of medical services for cardiovascular disease care. Elisa Lee of the University of Oklahoma is studying members of the seven tribes of Oklahoma. Thomas Welty at the Aberdeen Area Indian Health Service follows three Northern Sioux tribes. Barbara Howard of Medlantic studies Pima Indians from the Gila River and Salt River Indian communities.