[en] ive changes in plasma lipid profile have been studied in six patients undergoing aortobifemoral bypass. The second day after surgery, significant changes were: decreased levels of high density lipoprotein (HDL) cholesterol (by 55%), non HDL cholesterol (by 60%) phospholipid (by 50%), pre-beta-lipoprotein (by 70%), beta-lipoprotein (by 50%), apolipoprotein A1 (by 60%) and apolipoprotein B (by 55%). The magnitude of these changes correlated positively with serum levels of transferrin and negatively with serum levels of C-reactive protein. Triglyceride levels also showed a significant decrease (by 60%) while free fatty acids increased by 70%. Changes in triglyceride levels were not correlated with serum transferrin and C-reactive protein but showed a significant negative correlation with insulin levels. Our results suggest that both inflammatory and endocrine mediators are likely implicated in the postoperative changes in lipid profile.