The identification of cholesterol as a constituent of atheromatous plaques has aroused recurrent waves of suspicion that lipid metabolism is in some way responsible for the development of atherosclerosis and coronary artery disease. Lipids are transported in serum as constituents of three major classes of compounds: cholesterol and its esters, phospholipids, and triglycerides or neutral fat. Most investigations in recent years have centered about the notion that serum cholesterol plays a causative role in the development of coronary artery disease in spite of numerous studies focusing attention on triglycerides. Included in these studies are reports of increased turbidity, increased and prolonged chylomicronemia, and increased ratio of β- to α-lipoproteins. Although triglycerides rather than cholesterol are chiefly responsible for turbidity of serum and constitute an important fraction of β-lipoproteins, the quantitative estimation of triglycerides has been largely neglected in studies of serum lipids in coronary artery disease. The present research was