Lung specimens were obtained from 9 patients with shock lung (adult respiratory distress syndrome), immediately after death, and from 8 controls. They were analysed for phospholipid content anf for fatty acid composition of sphingomyelin and lecithin. We found an elevated phospholipid content in the affected lungs but a decreased dipalmitoyllecithin fraction of total lecithin as indicated by 127% elevated content of oleic acid in lecithin. As a consequence the relation between the palmitic acid and oleic acid moiety of lecithin shifted from 2.32 in the normal lungs to 1.64 in the diseased lungs. Since the content of dipalmitoyllecithin is closely related to the function of the surfactant system we conclude, that the alteration of surfactant function, observed in patients with adult respiratory distress syndrome may be at least in part a result of an altered surfactant metabolism, but we cannot rule out, that the findings represent an epiphenomenon in shock lung.