Abstract.Dietary n‐3 fatty acids modify the fatty acid composition of phospholipids of different cells and tissues from rats in diverse ways. Neutrophil and platelet phospholipids contain elevated amounts of 20: 5n‐3, but only relatively small changes occur in the levels of 22‐carbon n‐3 fatty acids. Conversely, dietary n‐3 acids result primarily in an increase in 22‐carbon n‐3 acids in heart, liver and kidney phospholipids. Platelets metabolize exogenous n‐6 and n‐3 fatty acids into a variety of different autocoids. However, it appears that only arachidonate and 20:5n‐3 are released from phospholipids upon agonist‐induced stimulation of phospholipases. Neutrophils metabolize arachidonate and 20: 5n‐3 in similar ways, both relative to phospholipid biosynthesis and the subsequent release of these acids for metab