Objective: To explore the effect and mechanism of breviscapine against myocardial ischemia/ reperfusion injury in rat. Method: 40 SD rats were randomly divided into sham operation group

ischemia / reperfusion group and breviscapine group. Rats in breviscapine group were injected with breviscapine 25

50 mg· kg1· d -1 respectively prior to ischemia /reperfusion. The other two groups were given normal saline instead of breviscapine equally in volume at a week before the operation. The myocardial ischemia /reperfusion model was established by ligating the left anterior descending branch of coronary artery. Apoptosis of myocytes was detected after operation in all groups by flow cytometry with Annexin Ⅴ and propidium iodiode （ PI ） staining. The ultrastructural alterations were observed under the transmission electron microscopy. Result: breviscapine could decrease the occurrence rate of myocardial apoptosis during ischemia /reperfusion injury obviously（ P < 0. 05

P < 0. 01）. The degree of injury on ultrastructures of myocardial cell in breviscapine group is rather alleviated compared with that in the ischemia /reperfusion group. Conclusion: breviscapine may protect myocardial cells during ischemia /reperfusion injury and the protective mechanism may be achieved by inhibiting myocardial apoptosis.