Cholesterol, high density lipoprotein (HDL) cholesterol and triglyceride concentrations were measured in 150 male survivors of first myocardial infarction and in 115 age and ethnic matched healthy controls. The total cholesterol concentration was higher in whites than in respective Asian groups and higher in patients than in controls (P less than 0.001). The ratio of cholesterol to HDL cholesterol was significantly higher in patients (P less than 0.001) and in both ethnic groups was a powerful independent predictor of cases. In Asians, the extent of coronary atheroma assessed by arteriography 2-12 weeks after infarction correlated independently with the total cholesterol concentration (P = 0.03). Thus, in Asian men, the lower level of total cholesterol compared to whites may be misleading. In Asian men the extent of atheroma correlated with the total cholesterol concentration and the relative risk of infarction increased with the ratio of total to HDL cholesterol. At a given level of cholesterol different ethnic groups may be at differing levels of cardiac risk and the cholesterol ratio may be a more appropriate means of inter-ethnic comparison.