Abstract: OBJECTIVE To explore the protective effects of Buxin Ruanmai Granules (BXRMG) on rats with myocardial ischemia caused by isoprenaline (ISO). METHODS The SD rat model of acute myocardial ischemia was developed by injecting isoproterenol hydrochloride (ISO) into subcutaneous tissue on the back and limbs. The effects of BXRMG on the displacements of ST region were observed at 1， 2， 3， 5， 10， 15， 20， and 30 mins after injection. Orbital blood was collected 30 minutes after modeling. Then， serum was separated and LDH and CK activities were determined and myocardial pathological morphology was observed. RESULTS The effects of BXRMG on ST region in myocardial ischemia induced by ISO indicated that LDH and CK level were improved significantly and histopathology was also improved. CONCLUSION Buxin Ruanmai Granules may protect the heart through strengthening the body's tolerance to ischemia， stabilizing the membrane and reducing the attacked areas from myocardial necrosis.