AIM: To investigate the antioxidative potential of propofol (an intravenous anesthetic with a chemical structure similarto phenol-basedfree radicalscavengers suchas vitaminE) during cardiopulmonary bypass(CPB). METHODS: Thirty adult patients referred for elective cardiac procedure with CPB were included and randomly allocated to a propofol group or a control group. Patients in the propofol group received propofol (0.1 mg·kg-1·min-1) intrave- nously for anesthesia maintenance, whereas those allocated to the control group received fentanyl 10 μg/kg intrave- nously and inhaled enflurane (1 %-1.5 %). Blood samples were collected at 7 time points: before the start of CPB, at 30 and 60 min of CPB, at the conclusion of CPB, 10 min after the administration of protamine, and 12 and 24 h after the cessation of CPB. Plasma levels of free F2-isoprostanes (sensitive markers of free radicals production) and complement C5a were determined by mass-spectrometricassay and enzyme immunoassay, respectively. Neu- trophil adhesion to endothelial cells was observed at ×200 magnificationunder a light microscope. RESULTS: Levels of F2-isoprostanes, complement C5a and neutrophil adhesion rate increased significantly during and after CPB in both groups. There were significantly higher levels of F2-isoprostanes, C5a, and more neutrophils adhering to endothelial cells in the control group than those in the propofol group, respectively. CONCLUSION: Cardio- pulmonary bypass is associated with a great production of damaging free radicals. Propofol may be beneficial both as an anesthetic and as a potent free radical scavenger in patients presenting pathologies associated with free radical reactions during CPB. AIM: To investigate the antioxidant potential of propofol (an intravenous anesthetic with a chemical structure similarto phenol-based free radical cavengers suchas vitamin E) during cardiopulmonary bypass (CPB). METHODS: Thirty adult patients referred for elective cardiac procedure with CPB were included and specifically allocated to a propofol group or a control group. Patients in the propofol group received propofol (0.1 mg · kg -1 · min -1) intrave nously for anesthesia maintenance, but those allocated to the control group received fentanyl 10 μg / kg intrave n nously and inhaled enflurane (1% -1.5%). Blood samples were collected at 7 time points: before the start of CPB, at 30 and 60 min of CPB, at the conclusion of CPB, 10 min after the administration of protamine, and 12 and 24 h after the cessation of CPB. Plasma levels of free F2-isoprostanes (sensitive markers of free radical production) and complement C5a were determined by mass-spectrometricassay and enzyme immunoassay, respecti vely. Neu- trophil adhesion to endothelial cells was observed at × 200 magnificationunder a light microscope. RESULTS: Levels of F2-isoprostanes, complement C5a and neutrophil adhesion rates increased significantly and after after CPB in both groups. -isoprostanes, C5a, and more neutrophils adhering to endothelial cells in the control group than those in those propofol group, respectively. CONCLUSION: Cardio-pulmonary bypass is associated with a great production of damaging free radicals. Propofol may be both as an anesthetic and as a potent free radical scavenger in patients presenting pathologies associated with free radical reactions during CPB.