The decline in coronary heart disease mortality apparently began around 1963 in the United States and increased in intensity in later years. In the 35-44 age groups the decline began somewhat later, perhaps around 1968. The decline has been found in all four race sex groups and in all age groups including the very old. This decline has also been noted in many other countries besides the United States. The decline of coronary heart disease mortality could obviously be a function of either a change in incidence or in case fatality or both. During the time of this decline in coronary heart disease mortality a great many changes were occurring both in the care of the cardiac patients and changes in risk factors. The fact that the decline occurred across all age as well as race, and sex groups as well as in many other countries suggested that one single factor may not have accounted for the decline.