Objective To explore the correlation among site of left anterior descending artery(LAD) ligation,infarct size and left ventricular function in establishing myocardial infarction model of swine.Methods LAD was surgically occluded at different percentage point of LAD varying from 30% to 70% in forty-seven mini-swine.Cardiac function was examined by left ventricular ejection fraction(LVEF) using echocardiography before and 1 hour after myocardial infarction(MI).Coronary angiography was performed for confirming the position of ligation after MI and the ischemic area was examined at the 4th week after MI.Linear regression analysis was used to analyse the correlation between LAD ligation point and infarct size or ventricular function. Results Thirty-nine of the 47 pigs survived from ventricular fibrillation.The correlation between percentage point of LAD ligation(x) and infarct size or ventricular function(y) was: y = 0.53x-5.43,r = 0.90(P<0.001) for infarct size(%);y = 65.88-0.55x,r = 0.87(P<0.001) for LVEF post-MI(%);y = 0.12 0.59x,r = 0.78(P<0.001) for decreased LVEF post-MI.Conclusion There is a significant correlation among LAD ligation site,infarct size,and LVEF,which makes it reasonable to determine the ligation site of LAD according to different study purposes in establishing MI model of swine.