Long chain n-3 PUFAs (polyunsaturated fatty acids) are found in fatty fish and in fish oils. Substantial evidence from epidemiological and case-control studies indicates that consumption of fish, fatty fish and long-chain n-3 PUFAs reduces the risk of cardiovascular mortality. Secondary prevention studies using long-chain n-3 PUFAs in patients post-myocardial infarction have shown a reduction in total and cardiovascular mortality, with an especially potent effect on sudden death. Long-chain n-3 PUFAs have been shown to decrease blood triacylglycerol (triglyceride) concentrations, to decrease production of chemoattractants, growth factors, adhesion molecules, inflammatory eicosanoids and inflammatory cytokines, to lower blood pressure, to increase nitric oxide production, endothelial relaxation and vascular compliance, to decrease thrombosis and cardiac arrhythmias and to increase heart rate variability. These mechanisms most likely explain the primary and secondary cardiovascular protection afforded by long-chain n-3 PUFA consumption. A recent study suggests that long-chain n-3 PUFAs might also act to stabilize advanced atherosclerotic plaques, perhaps through their anti-inflammatory effects. As a result of the robust evidence in their favour, a number of recommendations to increase intake of long-chain n-3 PUFAs have been made.