Coronary heart disease mortality declined by 17 percent and 14 percent for New Zealand European men and women respectively between 1968 and 1978. The fall occurred in all age groups and in Maoris and cannot be attributed to change in diagnostic fashions. The decline has been associated with a decrease in the consumption of diary products and more recently with a levelling off of cigarette smoking, an increased awareness of the importance of treating hypertension, and an apparent increase in habitual physical activity in the community. There have also been improvements in the medical management of patients with coronary heart disease which may be contributing to the continuing decline in mortality rates. A programme to monitor trends in CHD incidence and case fatality and the level of risk factors in the community is required to elucidate the reasons for the decline in CHD mortality.