In the present work we investigated the effect of regular physical exercise on the activities of erythrocyte antioxidant enzyme, plasma total radical-trapping antioxidant potential(TRAP) and plasma level of lipid peroxidation(malondialdehyde, MDA) in 64 healthy male, aged 34-67 years. The study population were divided in two groups: small amount of exerciser(exercise time less than 10min/d) and moderate amount of exerciser(exercise time more than 20min/d) according to their physical exercise habits measured by a questionnaire. Erythrocyte superoxide dismutase(SOD), glutathione peroxidase(GSH-Px) and catalase(CAT), plasma TRAP, as well as plasma MDA were determined. Erythrocyte GSH-Px and plasma TRAP were higher in moderate amount of exercisers than those in small amount of exercisers by 17% and 26%, respectively. No significant differences were observed in erythrocyte SOD, CAT and plasma MDA between the two groups. Mean exercise time was positively correlated with the erythrocyte GSH-Px activity and plasma TRAP significantly. The results would sugest that regular moderate exercise enhances antioxidant defences against reactive oxygen species and may increase the likelihood of a healthier life span.