Type V hyperlipemia is not very common. The series of 54 cases descrubed here is the largest reported to date. Our observations were recorded when lipidograms showed the presence of chylomicrons and a large pre-beta-lipoprotein spot in the serum of fasting subjects. Type V hyperlipemia was often combined with other metabolic syndromes such as diabetes, hyperuricemia or gout, or obesity. Chronic alcoholism was also noted in half our subjects, in whom hyperlipemia quickly regressed after alcohol consumption ceased. Ischemic arterial complications, chiefly coronary, were found in one third of our cases, and the vascular risks accompanying this type of hyperlipemia rose considerably in patients with high blood pressure. Various type of treatment were administered, but all subjects were put on a special diet, comprising either the elimination of alcoholic drinks only, or, in addition to this, reduced carbohydrate or calorie intake. As a rule, these measures resulted in a distinct regression of lipid anomalies. Clofibrate or derivatives proved effective in cases where hyperlipemia failed to respond to dietary measures.