The effect of Shengmaisan (SMS) on 62 acute viral myocarditis patients and its peroxidation damage was studied. The results revealed that the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in blood were decreased and the content of malondialdehyde (MDA) in plasma was increased in acute viral myocarditis patients in comparison with the healthy controls (P < 0.001). 62 acute viral myocarditis patients were divided into two groups: SMS group and placebo group. After treatment, both SOD and GSH-Px activities were increased and the level of MDA decreased (P < 0.001) in SMS group, while those in placebo group were not changed (P < 0.05). The results suggested that the myocardial damage of viral myocarditis is closely related with lipid peroxidation SMS acts as an effective free radical scavenger and anti-lipid peroxidation drug. SMS could prevent the damage of myocardia and might be taken as one of the effective therapeutic methods in treatment of acute viral myocarditis.