Effects of prednisolone (PR) and vitamin E (VE) on oxidative stress and antioxidant systems were investigated in endotoxemic rabbits. Forty rabbits were used and divided into four equal groups. Group I served as the control group. In group II, lipopolysaccharide (LPS, 100 mug/kg/h) was infused for 6 hours, whereas rabbits of groups III and IV received prior treatments with subcutaneous injection of prednisolone (10 mg/kg) (group III) or with intraperitoneous injections of vitamin E (10 mg/kg) for 4 consecutive days (group IV). Serum, liver, heart and kidney samples were obtained at 8 hours after infusion. Malonedialdehyde (MDA), glutathione (GSH) concentrations and superoxide dismutase (SOD), catalase (CAT) activities were spectrophotometrically determined in tissues plus in serum (for MDA).