A retrospective review was made of all death certificates certified to coronary heart disease, all other cardiovascular deaths, and all non-traumatic but possibly sudden deaths certified by the coroner. The review included autopsy records, coroner's reports, hospital records, information from certifying physicians, and interviews with next-of-kin or witnesses. A determination was made of the contribution to the decline of out-of-hospital sudden death and prior history of heart disease, other diseases, and possibly cigarette smoking. The changing mode of death for in-hospital deaths was also evaluated.