Effects of saponin isolated from the leaves of Acanthopanax senticosus (ASS) on myocardial infarct size were studied in acute ischemic dogs. The results showed that ASS (in a dosage of 25.50 mg/kg, iv) could significantly reduce the sizes of acute myocardial infarcts and decline the serum CK and LDH activity at 6h after ligation of LAD. It could also decrease the serum FFA levels at 3h and 6h after LAD occlusion.