Examinations of 'healthy' men in Helsinki and in rural west and east Finland in 1956 included estimation of total cholesterol and that in the HDL and beta fractions separated by electrophoresis. Vital status to the end of 1980 has been ascertained for all but eight of the 526 men aged 35-61 and for all but two of 261 men aged 30-34 at entry. Among the men aged 35-61, in 24 years 155 died, 63 from coronary heart disease; among the men aged 30-34, 36 died, 16 from coronary heart disease. All causes and coronary death rates were highest in east Finland where HDL cholesterol was also highest. Coronary death rates were not related to HDL cholesterol in east or west Finland but 16 men dead from coronary heart disease in Helsinki tended to have low HDL values. Consideration of five other entry characteristics did not change the picture with regard to HDL-mortality relationships. Solution of the multiple logistic equation using all those variables found the probability of 24-year coronary death was not significantly related to HDL but was significantly related, positively, to the non-HDL cholesterol concentration. HDL and total cholesterol mean values for men of the same age in the same area of Finland, with lipoprotein separation by the new recommended methods, agree closely with the means recorded in 1956. These 24-year findings are not necessarily in conflict with reports in the literature on an inverse relationship between coronary heart disease incidence and HDL cholesterol based on much shorter periods of follow-up and few data on mortality.