Background and objective: Extremity surgery with tourniquet to provide a bloodless field may be a good human model for ischaemia reperfusion (IR) injury. The aim of this study was to investigate the effects of three different modes of propofol use on tourniquet induced IR injury in lower extremity operations. Methods: Thirty-three consecutive ASA Grade I and 11 patients were randomized into three groups of I I patients each. In the spinal group (Group S), after intrathecal anaesthesia, sedation was given with a propofol infusion at 2 mg kg(-1) h(-1) after a 0.2 mg kg(-1) bolus dose and fentanyl 100 mu g. In the general (Group G) and TIVA (Group T) groups, general anaesthesia was induced with propofol 2 mg kg(-1) with fentanyl 100 mu g and maintained with inhalation of halothane or infusion of propofol respectively. Venous blood samples were obtained at different time points for measurements of plasma malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) levels. Results: Plasma MDA levels were increased significantly in the Group G at I min before tourniquet release and 5 and 20 min after tourniquet release compared with before induction of general anaesthesia (baseline). Before intrathecal anaesthesia and before induction of general anaesthesia significantly decreased levels of MDA were observed both before and after tourniquet release compared to baseline. Plasma SOD and CAT concentrations were decreased significantly only at tourniquet release in the Group G compared with baseline. In the Groups S and T these enzymes were not changed significantly. Plasma GPx levels were not altered in any groups. Conclusion: Propofol administration may inhibit lipid peroxidation and restore antioxidant enzyme levels in extremity surgery requiring tourniquet application.