The purpose of this study was to investigate the effects of different intensities of exercise on α-tocopherol and thiobarbituric acid reactive substance (TBARS) levels in the plasma and liver of rats. Male Wistar rats were divided into a sedentary control group and exercise groups. The exercise groups were forced to exercise by treadmill running at 30%, 60% and 80% of maximum oxygen uptake (VO₂max) for 120 minutes. Some animals in each exercise group were sacrificed immediately and others at 6 hours after the exercise period, α-Tocopherol levels in the plasma and liver were analyzed by HPLC. Plasma α-tocopherol levels of rats sacrificed immediately after the exercise period decreased significantly in the 60% and 80%VO₂max groups compared to controls. In all exercise groups, plasma α-tocopherol levels were significantly higher 6 hours after the exercise period compared to those sacrificed immediately after the exercise period. Liver a -tocopherol levels were also lower in all exercise groups 6 hours after the exercise period, especially in the 80% VO₂max exercise group. There were no differences in TBARS levels between the control and exercised groups. These results indicate that acute exercise induces oxidative changes in the liver, but the liver is able to compensate by increasing the consumption and release of α-tocopherol to neutralize any damage.