animals suggest that atherosclerosis may be reversed to some extent. Patients with high levels of serum cholesterol, and probably also those with elevated serum triglycerides, are in a high-risk group relative to the development of atherosclerotic heart disease and myocardial infarction. Accordingly, it would seem wise to try to reduce these high concentrations of serum lipids with the aim of influencing the atherosclerotic process. Therapy of hyperlipidemia should be combined with active measures to control all other factors that may be related to atherogenesis, such as hypertension, obesity, physical inactivity, etc. REDUCTION OF SERUM LIPIDS Serum lipid levels can be influenced by diet, hormones, and a number of pharmacologic agents. Reduction of serum lipids can be accomplished by several mechanisms. The dietary supply of lipids can be reduced, absorption can be diminished, or tissue synthesis of specific lipids can be inhibited. Degradation and excretion of lipids can be stimulated. A redistribution of lipids can occur, with an increase in lipids in tissues at the expense of those in the circulating blood. The concentration of cholesterol in serum is tile resultant of the amount ingested and absorbed plus the amount synthesized, as related to the amount degraded to bile acids and excreted in the bile as such, or as cholesterol, and the amount utilized or stored in the tissues. Some of the bile acids and