A clinical study on 59 remote myocardial infarction cases were divided randomly into treated group (31 cases) and normal control group (28 cases). Treated group used intravenously injected Ligustrazine 160 mg a day for 10 days. The plasma lipid peroxidation (LPO), superoxide dismutase (SOD) and sulfhydryl group were measured before and after treatment in the treated group, in comparing with normal control group. The results showed the levels of LPO significantly reduced (P < 0.01), and SOD, sulfhydryl group was obviously increased after Ligustrazine administration (P < 0.05). Attack of angina pectoris was reduced. Between these two group, the difference was significant (P < 0.05). Mechanism of Ligustrazine in reducing LPO and increasing SOD could be the inhibiting of platelet aggregation, regulating the TXA2/PGI2 ratio in plasma, protecting myocardial cell membrane and improving the myocardial ischemia. Ligustrazine could reduce the production of LPO due to the accelerating clearance of oxygen free radical.