Five patterns of hyperlipoproteinemia are described; each may represent more than one clinical and biochemical abnormality. This heterogeneity notwithstanding, the patterns are useful for genetic and clinical purposes and allow treatment to be individualized. Patients with types III, IV and V respond very favorably to weight reduction, although weight reduction and caloric restriction does little for those with the type II pattern. Diets high in carbohydrate and low in fat are helpful to patients with type I but cause increasing hyperlipemia in most of those with type IV. Diets balanced in fat and carbohydrate are effective in treatment of patients with type III, but the amounts of fat and carbohydrate makes little difference to those with type II. The patient with type V does best when both fat and carbohydrate are removed from the diet and replaced with protein. None of the presently available drugs is effective in all the hyperlipoproteinemias. Atromid-S is particularly effective in type III, only modestly effective in type II and ineffective in type I. The physician in 1968 will find it helpful and sometimes necessary to seek information beyond the determination of plasma lipids in evaluating some patients with hyperlipidemia. Lipoprotein patterns can be very useful to him in differential diagnosis, in prognosis and further pursuit of the familial presence of some of these trying clinical problems. Perhaps of most importance, he will find them of great practical utility for the selection of appropriate drug and diet therapy. © 1968.