1. Population studies and clinical trials provide compelling evidence that omega-3 (omega3) fatty acids have cardioprotective effects. The strongest evidence is from DART and GISSI-P, two secondary prevention trials in patients with previous myocardial infarctions. Data from these trials support a reduction in ventricular fibrillation as a primary mechanism for the decreased incidence of myocardial infarction. 2. Evidence suggests that w3 fatty acids may also provide protection against stroke, particularly ischaemic stroke. 3. The cardioprotective effects of omega3 fatty acids relate to improvements in blood pressure, cardiac function, arterial compliance and vascular function, as well as improved lipid metabolism, antiplatelet and anti-inflammatory effects. 4. Clinical trials in humans have shown that eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have different haemodynamic properties. Docosahexaenoic acid may be more favourable in lowering blood pressure and heart rate, as well as improving vascular function. However, the effects of EPA and DHA may also differ depending on the target population.