Abstract: To study the effects of batroxobin on coronary circulation and cardiac performancein acute myocardial ischemia,Batroxobin was given intravenously to dogs with experimental coronarystenosis.A dose-dependent increase of coronary blood flow(CBF)was observed.Forty minutes afterbatroxobin(2 BU·kg^-1 at infusion rate 0.1 BU·kg^-1·min^-1)administration,CBF increased by12%(P<0.05),small coronary resistance(R_S)decreased from 4.1±0.5 to 3.2±0.5 mmHg·min·ml^-1(P<0.01),while large coronary resistance(R_L)changed insignificantly from 3.9±0.8 to 3.8±0.7mmHg·min·ml^-1(P>0.05).Two hours following drug administration,the changes in CBF, R_S and R_L still remained and R_T decreased by 13%(P<0.05).The + LV(dp/dt)_max and -LV(dp/dt)maxincreased by 14% and 16%(P<0.05)respectively compared with those in control group.It isconcluded that batroxobin improves the ischemic canine coronary circulation and cardiac performanceby way of lowering the small coronary resistance and thus increasirig CBF.The data also suggest thebenificial effect of batroxobin in acute myocardial ischemia.