Serum cholesterol and triglyceride levels may vary widely in a given patient, and therefore both of these lipid determinations should be repeated for initial evaluation. Later, the response of lipid values to diet and to drugs provides more information on the individual characteristics of a hyperlipoproteinemia than "typing" from one lipid evaluation. The type may actually change with lipid levels, whereas the basic tendencies to increased betalipoproteins (evaluated as cholesteremia) or prebetalipoproteins (evaluated as triglycerides) are more constant features in a patient. Alimentary conditions in most cases influence hyperlipemias, whether primary or secondary. Total caloric intake is a major factor in inducing augmented triglycerides in predisposed people. Hypertriglyceridemia is rare before 20 and not frequent in women. On the other hand, familial hypercholesteremia is present from the first weeks of life. Diet is of little help in these cases. When hypercholesteremia is related to food habits it usually appears after the third decade. The amount of fats rich in saturated fatty acids appears to be the chief causative factor in this regard. However, it is possible that genetic factors also affect the degree of alimentary influence on cholesterol level over many years. The use of hypolipemic drugs does not obviate the need for appropriate diet. If the prevention of early coronary disease is to be successful it should start in young people before the first clinical symptoms appear.