An international comparison of trends in mortality from coronary heart disease (CHD) since 1968 shows a sizeable decline in the U.S.A., Australia, New Zealand, Finland, Canada, Belgium and Japan. By contrast England, Wales and Scotland had shown no evidence of decline in CHD mortality until 1979. This has resulted in a marked deterioration in the CHD ranking of Scotland and England and Wales relative to other countries. Sweden, Hungary, Poland, Yugoslavia, Bulgaria, Rumania and the U.S.S.R. have all had increases in CHD mortality. There are many possible reasons for these changes. In general, countries that had had a decrease in CHD mortality have experienced changes in the type and/or quantity of fat in the national diet. The changes in CHD mortality in Sweden and Japan are out of line with the pattern in other countries. There is some evidence that changes in smoking and blood pressure control may have contributed to changes in CHD mortality. Changes in physical activity may have also played a part.