Based on epidemiological, experimental and physiological evidence, this review examines whether omega-3 fatty acids (omega-3-PUFA) are cardioprotective and whether they are therefore relevant to the primary prevention of cardiovascular diseases. The high intake of omega-3-PUFA among Greenlandic Eskimos has been supposed to be a key factor for their low mortality rate of coronary heart disease (CHD). Other ecological studies from Norway and Japan suggest that higher fish consumption might be cardioprotective. Three cohort studies have shown an unequivocal inverse relation between fish-intake and CHD mortality, while two others--possibly for methodological reasons--have not shown clear overall associations. Several biological effects of omega-3-PUFA are known which may moderate and influence positively the pathogenesis of atherosclerosis. However, double-blind trials with clinical endpoints are not yet available to confirm these effects. For the time being, fish oil capsules should not be recommended as cardioprotective dietary supplementation, because some uncertainty about their long-term safety and dosage remains. Fish consumption is safe and modifies the FA-pattern of the diet favourably. From the point of view of prevention, rising fish intake up to twice or three times weekly can therefore be recommended for people residing in Switzerland.