The strategy for the diagnosis of hypertriglyceridaemia comprises three successive steps. First, the physician should confirm the biological abnormality by at least one additional blood sample taken after an overnight fast; recent data, however, suggest that postprandial hypertriglyceridaemia may also represent a cardiovascular risk factor. Second, the phenotype of hypertriglyceridaemia should be considered as either isolated high triglyceride levels or hypertriglyceridaemia combined with hypercholesterolemia may be present; the combination of hypertriglyceridaemia with a low HDL cholesterol concentration or its association with the metabolic or insulin resistance syndrome should also be investigated. Third, all should be done in order to find the etiology of the hypertriglyceridaemia (by determining its genetic or nutritional origin, by excluding possible underlying pathologies, by looking for drugs able to increase serum triglyceride levels). These various steps should help the physician to take the final decision of treating one particular patient as well as to chose the most appropriate, nutritional or pharmacological, treatment.