SummaryThe role of blood lipids in the pathogenesis of coronary atherosclerosis seems to be substantiated by pathologic, experimental, and clinical data. Although hypercholesterolemia is the main factor involved, studies on blood lipids in angor pectoris suggest that hypercholesterolemia is the result of more than one single metabolic disorder. Thus, the sensitivity of blood lipoproteins to heparin as well as the vitamin A loading test help to differenciate 1) hypercholesterolemia with abnormalities within the first steps of lipid metabolism from 2) hypercholesterolemia without such abnormalities.The first type of hypercholesterolemia, which is close to idiopathic hyperlipemia, is very sensible to dietary changes. The second type, which is connected with idiopathic xanthomatous hypercholesterolemia, is not affected by changes in. lipid intake.The possible multiplicity of atheromatogenous hypercholesterolemia implicates practical consequences in diagnostic and therapeutic problems involved in the management of subjects prone to develop atherosclerosis.