:Objective To investigatethe effect of TCI of propofol(Cp 1.2 μg/ml)starting from the end oftemporary occlusion of the cerebral artery and maintained until the end of operation onantioxidative effects of brain during cerebral ischemia-reperfusion injury in patientsundergoing elective clipping of intracranial aneurysm.Methods Thirty ASA Ⅰ or Ⅱ patients,aged 26-64 yr,weighted 53-73 kg,undergoing electiveintracranial aneurysm clipping were randomly divided into 2 groups(n = 15 each): controlgroup(group C)and propofol postconditioning(group P).A catheter was placed in thesubarachnoid space at L_(3,4) interspace for CSF pressure monitoring and collection of CSFsamples.Radial artery was cannulated for MAP monitoring.ECG,HR,MAP,SpO_2,P_(ET)CO_2 andBIS were continuously monitored.Anesthesia was induced with midazolam,propofol,fentanyland rocuronium and maintained with 0.5%-2.0% sevoflurane,iv infusion of fentanyl andintermittent iv boluses of vecuronium.In group P TCI of propofol(Cp 1.2 μg/ml)was started from the end of temporary occlusion of cerebral artery andmaintained until the end of operation.Meanwhile the sevoflurane concentration wasdecreased and BIS was maintained at 40-60.CSF pressure was measured before induction ofanesthesia(T_0),immediately after occlusion of cerebral artery(T_1),immediately(T_2)and at30 min(T_3)and1 h(T_4)after removal of cerebral artery occlusion and at the end of operation(T_5).CSFconcentrations of F_2-isoprostances(F_2-IsoPs)(by ELISA)and α-and γ-tocopherol(α-T,γ-T)weremeasured at T_0,T_3,T_5 and 24 h afteroperation(T_6).Results CSF pressure was significantly lower at T_3 and T_4 in group P than in group C.The CSF concentrations ofα-T andγ-T were significantly decreased at T_3,T_5 and T_6 as compared with the baseline at T_0 in both groups.There was nosignificant difference in α-T concentration between the twogroups;while the γ-T concentration in CSF was significantly higher atT_3,T_5 and T_6 in group P than in group C.The CSF concentrations of F_2-IsoPs weresignificantly increased at T_3,T_5 and T_6 as comparedwith the baseline at T_0 in both groups and were significantly lower in group P than ingroup C.Conclusion TCI of propofol with Cp at 1.2 μg/ml starting from the end of temporary cerebral artery occlusionand maintained until the end of operation can enhance the antioxidative effects of brainin patients undergoing clipping of intracranial aneurysm. Key words: Propofol; Reperfusioninjury; Brain; Oxidation-reduction