Objective To observe the effect of Buzhang Naoxintong Capsule on cardiac function and infarct size in rabbits with acute myocardial infarction.Methods Forty two New Zealand white rabbits were randomized into the sham operation group

control group and drug group

with 14rabbits in each.Ligation of the left anterior descending artery（LAD）was adopted to establish acute myocardial infarction model and the sham opertion group was not ligated.Six models were successfully established in each group.The sham operation group and control group were given conventional feed.Buzhang Naoxintong Capsule was added in the drug group

1capsule once

three times daily.The experimental period lasted for 3weeks.Echocardiography was given to the rabbits on the 2nd and 21st day of infarction.Left ventricular and diastolic diameter（LVDd）

left ventricular and systolic diameter（LVSd）

and left ventricular ejection fraction（LVEF）were determined.On the 21st day of infarction

the rabbits were killed and the infarct size was tested.Results Left ventricular anterior wall and apical was darkening and pulse was weakened after the ligation and model establishment.Electrocardiogram showed ST-segment arched upward and integrated with the T wave.On the 21st day of infarction

LVEF significantly increased（P<0.05）and the infarct size significantly decreased（P<0.05）in the drug group as compared with the control group.Comparing with the 2nd day of infarction

the LVEF significantly increased on the 21st day of infarction in the drug group（P<0.05）.Conclusion Buzhang Naoxintong Capsule could obviously decrease the infarct size

increase the LVEF and improve the cardiac function.