When compared to values obtained in 24 age-matched normal weight normolipidemic control subjects, plasma fibronectin level was not significantly changed in the 28 patients with peripheral arterial disease, although endothelial cell-derived factor VIII related antigen was found to be obviously increased. On the other hand the 15 patients with obliterative atherosclerosis of the lower limbs who were hyperlipidemic (mainly hypertriglyceridemic) displayed a plasma fibronectin level (46.3 +/- 2.8 mg/dl) which was higher than the mean values recorded in both control subjects (36.2 +/- 1.66 mg/dl) and in normolipidemic patients with peripheral arterial disease (34.5 +/- 4.14 mg/dl). The results suggest that an increased level of plasma fibronectin should be connected rather to a peculiar pattern of hepatic protein synthesis occurring in overweight and hypertriglyceridemic subjects than to a release of this glycoprotein from an ongoing arterial lesion.