In recent years there has been a growing interest in the use of omega-3 polyunsaturated fatty acids as medical therapeutic agents, and a multitude of epidemiological and clinical studies have evaluated their role in health and disease. A drug containing high concentration of omega-3 polyunsaturated fatty acids has been approved for the treatment of hypertriglyceridemia and following myocardial infarction in some European countries. Furthermore, there is a growing body of evidence suggesting that these fatty acids may be of benefit in several other diseases. To date, the majority of research has focused on cardiovascular diseases including hypertension, atherosclerosis and the prevention of sudden cardiac death, where these fatty acids may be useful. In addition, several studies have suggested a beneficial effect in severe acute and chronic inflammatory diseases, particularly rheumatoid arthritis and immunoglobulin A nephropathy, although the results have not been consistent. Finally, the role of omega-3 polyunsaturated fatty acids in the structure and function of nervous tissue has prompted investigations on their effect on neurological development of premature and young infants and their use as therapeutic agents in psychiatric disorders. In this article we review the scientific evidence for the role of omega-3 polyunsaturated fatty acids in clinical medicine.