Exhaustive endurance exercise in adult female albino rats (C-Ex) increased the generation of free radicals (R.) in the myocardium, probably through enhanced oxidative mechanisms. Free radical mediated lipid peroxidation measured in the form of tissue MDA content also increased in C-Ex animals, suggesting the exercise-induced oxidative stress in these animals. Dietary supplementation of Vit E, for a period of 60 days significantly increased Vit E incorporation into the serum and myocardium, more so in the myocardium. Vit E supplementation to exercising animals completely abolished the radical production. The protection of Vit E against oxidative stress appears to be not mediated through the improvement of antioxidant mechanisms by enzymes like SOD, catalase and Se-GSH Px. However the non Se-GSH Px, the enzyme involved in the reduction of endoperoxides increased significantly in control and Vit E fed animals in response to exercise. The protection of Vit E against exercise-induced oxidative stress was correlated with its multivarious activities like a) scavenger of free radicals; b) inhibition of lipoxygenases; and c) reduction of peroxides in association with lipoxygenases. These studies indicate that dietary supplementation of Vit E protects the animals from the possible oxidative damages of endurance exercise.