ABSTRACT: Objective: To explore protective effect and mechanism of breviscapine against myocardial ischemia reperfusion injury in rats. Methods: 40 SD rats were divided into sham operation group

ischemia reperfusion group and breviscapine group randomly.Rats in breviscapine group were injected with breviscapine 25、50mg.kg1.d-1 respectively prior to ischemia reperfusion .other two groups were given NS instead of breviscapine equally at a week before the operation. Myocardial ischemia reperfusion injury model was established. Apoptosis of myocytes was detected after operation in all groups by flow cytometry with AnnexinⅤ-EGFPand propidium iodiode ( PI) staining. The ultrastructural alterations were observed under the transmission electron microscopy. Results : breviscapine could decrease the occurrence rate of myocardial apoptosis during ischemia reperfusion injury obviously（P＜0.05，P＜0.01）;The degree of injuring on ultrastructures of myocardial cell in breviscapine group is rather alleviated than in ischemia reperfusion group.Conclusion : breviscapine may protect myocardial cells during ischemia reperfusion injury and the protective mechanism may be obtained by inhibiting myocardial apoptosis.