Following severe multiple trauma, decreases were observed in a) Free cholesterol, b) Cholesteryl esters, c) Total phospholipids, and d) Lysolecithin. Comparatively slight changes in coagulation parameters did not differ regardless of whether pulmonary complications developed. In contrast, increased fibrin lipid complexing was more closely correlated with clinical data, because: a) Plasmatic lipids, particularly triglycerides complexed with fibrins, were elevated severalfold in patients with adult respiratory distress and fat embolism syndromes when compared with multiple trauma patients without pulmonary complications. This was independent of plasma lipid levels. b) Plasmatic triglycerides complexed with fibrins were significantly higher in patients who died than in those who survived. The considerable changes in the plasma lipid pattern following severe trauma suggest the presence of an abnormal lipoprotein with increased affinity to fibrin, thereby inhibiting fibrinolysis. This might well be one pathogenic mechanism in the development of post-traumatic respiratory distress syndrome.