Up to recently arteriosclerosis was regarded as an incurable state—the inevitable result of advancing age and the remorseless effect of wear and tear or "rusting out" of the arteries. Arteriosclerosis in its various forms ranks first as a cause of death and disease in the United States. Accumulated evidence refutes these fatalistic resignations, stressing the concept that atherosclerosis is a metabolic error, in which disorders of the blood lipids and lipoproteins play a dominant role. The work of numerous investigators1has shown that arteriosclerosis whose clinical aspects are better known as atherosclerosis2is a reversible disease in the experimental animal3and that it shows equally promising therapeutic responses in humans.4 Recent studies5have indicated that an excess of ingested dietary fats, or persistent alimentary hyperlipemia, appears to be the factor responsible for atherosclerosis (although I believe that there are several factors). Numerous opponents have countered