An experiment utilizing Cobb-500 male broilers was conducted to evaluate the effects of vitamin E supplementation at various concentrations on malonyldialdehyde (MDA) as an indicator of lipid peroxidation, serum and liver concentrations of antioxidant vitamins and some minerals of broilers reared under heat stress (32 degreesC). One day-old 150 male broilers were randomly assigned to 5 treatment groups, 3 replicates of 10 birds each. The birds received either a basal diet or basal diet supplemented with vitamin E (dl-alpha -tocopherol acetate) at 62.5, 125, 250, or 500 mg/kg of diet. Increased supplemental vitamin E linearly increased serum vitamin E and A, but decreased (P = 0.001) MDA concentrations. Increasing dietary vitamin E supplementation also resulted in linear increases in liver vitamin E and A concentrations, but linear decreases in MDA concentrations (P = 0.01). Increasing dietary vitamin E caused a linear increase in serum concentrations of Fe and Zn (P = 0.001), but a decrease in serum concentration of Cu (P = 0.001). Results of the present study conclude that in broiler chicks reared under heat stress a 250 mg of vitamin E supplementation can be considered as a protective management practice in a broiler diet, reducing the negative effects of beat stress.