Objective To explore the protective effect of Breviscapine on myocardial ischemia reperfusion injury（MIRI） in rabbits and its mechanism.Methods Nineteen rabbits were randomized into three groups:sham operated group （n=6）

ischemia/reperfusion model group （n=7）

and Breviscapine treatment group （n=6）. The ischemia/reperfusion models were prepared with the thread-ligation of left anterior descending coronary artery. Five minutes before the ligation

the treatment group was treated with the ear intravenous injection of Breviscapine. The myocardial ultrastructure of rabbits; changes of serum lactic acid （LA） and non-esterified fatty acid （NEFA） of the ventriculus dexter

and the LA

NEFA and adenosine triphosphate （ATP） in the myocardial tissues were detected.Results Compared with the sham operated group

the content of LA and NEFA in the serum and myocardial tissues in the model group was significantly increased （P<0.01 or P<0.05）

the content of ATP in the myocardial tissues was significantly decreased （P<0.01）

and the myocardial ultrastructure was significantly injured. Compared with model group

the content of LA and NEFA in the myocardial tissues in the treatment group was significantly decreased （P<0.01 or P<0.05）

the content of ATP in the myocardial tissues was significantly increased （P<0.01）

and the injury of myocardial ultrastructure was significantly relieved.Conclusion Breviscapine is effective in the protection of myocardial tissues injured by ischemia and reperfusion through improving the cardiac energy metabolism and protecting the structure of mitochondria.