Female first-degree relatives of CHD patients differed, after the age of forty, from the normal control population by their low HDL cholesterol. Between the ages of 20 and 40 years a slight but significant increase in HDL triglycerides was observed. Except for hormonal contraception which induces significant lowering of HDL cholesterol in the first degree relatives, the observed differences in HDL lipids did not seem related to environmental factors but rather to be genetically determined. In contrast, the low HDL cholesterol observed in the wives of the CHD patients appeared to be related to differences in alcohol intake.