In discussion of prostaglandins and cardiovascular diseases attention is directed to the structures of the main prostaglandins biochemical synthesis prostaglandin metabolism and prostaglandins and cardiovascular diseases. In general the favorable influence of polyunsaturated fatty acids on the atherosclerotic process can be explained by means of the lipid-filtration theory. An additional theory is proposed here according to which the prostaglandins (E1 and F) synthesized in the organism from polyunsaturated fatty acids play a part in the prevention of atherosclerosis and thrombosis. This effect of prostaglandins would occur in the presence of divergent pathogenic factors e.g. platelet adhesion and aggregation vasoconstriction and dilatation hypertension lack of physical exercise mental stress smoking poor condition of the heart muscle and diminished coronary flow. It is postulated that the synthesis of certain prostaglandins is promoted if the dietary supply of the precursors is increased. (Summaries in ENG FRE GER)