Summary 　In epidemiological and clinical trials, fish oil rich in ω3 polyunsaturated fatty acids（PUFAs） or ω3 PUFAs have been shown to reduce the incidence of coronary heart disease. Recently, a large-scale, prospective, randomized clinical trial, the Japan eicosapentaenoic acid（EPA）Lipid Intervention Study（JELIS）, demonstrated that highly purified EPA, the only class of ω3 PUFAs used clinically to treat hyperlipidemia, significantly reduces the incidence of major coronary events, via cholesterol- independent mechanisms. As an anti-atherogenic effect, we previously demonstrated that EPA suppresses small dense LDL, oxidized LDL, an inflammatory marker, an index of arterial stiffness, and endothelial adhesion molecules, and increases the secretion of adiponectin in patients with metabolic syndrome. Therefore, to prevent the onset of cardiovascular diseases, it is important and effective to recommend the intake of fish oil and ω3 PUFAs in dietary therapy and administration of highly purified EPA in lipid management even in Japanese subjects.