In a healthy population, comparison of the lipoprotein lipid profile between subjects who were aware of the existence of cardiovascular disease among their relatives with the subjects who were not showed that the men in the former group had lower HDL cholesterol (1.3 mmol/l p less than 0.05) than men without a familial history of CHD (1.41 mmol/l). The difference was not significant in women. The values were within the normal range and there was an overlap of individual HDL cholesterol levels between the groups. This observation did however demonstrate that familial history of CHD was associated with lower HDL cholesterol and that low HDL cholesterol could play a significant role in certain families at risk.