The aim of the study was to verify the hypothesis that β-carotene, vitamin E, vitamin C administered individually or in combination may differently modify their levels in blood plasma being also markers of the oxidative stress. Male Wistar rats were supplemented antioxidants per os (α-tocopherol - 2 mg/d, ascorbic acid – 12 mg/d, β-carotene – 1 mg/d), both individually or in combination of 2 or 3, for 14 days. During experiment half of the animals in each group (n=8) were subjected by treadmill exercise for 15 minutes at the speed 20 m/min, to cause oxidative stress. Vitamins in rat plasma were assessed by the high-performance liquid chromatography (HPLC). Results suggest that vitamin E and C supplemented simultaneously may provide some benefit during physical exercise. The significant influence of administered α-tocopherol acetate and physical exercise on the level of α-tocopherol in the plasma was observed. Thus only the concentration of α-tocopherol in blood may be treated as a marker of oxidative stress.