The relationship of socio-economic status (SES) indicators and coronary risk factors (RFs) with coronary heart disease (CHD) prevalence was examined in 5 620 subjects aged 20-60 years who participated in the Coronary Risk Factor (CORIS) baseline study. Education and income (with some exceptions in males) were strongly and inversely related to hypercholesterolaemia, low high-density lipoprotein cholesterol, hypertension, smoking, overweight and prevalence of angina pectoris. In contrast, type A behaviour was positively associated with higher income and education. Females showed stronger SES-RF relationships than males. Town-dwelling females were more likely to be smokers, and had a higher prevalence of angina pectoris and myocardial infarction. The lowest overall prevalence of RFs, angina pectoris and myocardial infarction was found in the professional and managerial categories for both males and females. The SES indicators had little or no independent effect on CHD prevalence in multivariate logistic analyses after inclusion of the standard RFs. We conclude that these indicators relate to RFs, and through them to CHD.