Aim To elucidate whether ischemia and reperfusi on can induce cardiomyocytes apoptosis and the relation between polymorphnuclear n eutrophils (PMN) infiltration and cardiomyocytes apoptosis. The effect of ische mic preconditioning on apoptosis was also investigated. Methods Forty eight male Wistar rats were ra ndomly assigned to one of the following four groups: I+1h R group, I+2h R group , I+3h R group and IP group. The following variables were measured: cardiac fu nction, infarct size, PMN counts, myocardial myeloperoxidase activity and ap optotic cell in dex. Results Ischemia and reperfusion caused obvio us cardiac function injury, PMN infiltration and cardiomyocytes apoptosis, and heart injury increased as the reperfusion continued; ischemic preconditionin g significantly reduced heart injury and apoptosis. Correlative analysis betwee n PMN count and apoptotic index suggested a significant positive correlation ex isted between PMN infiltration and cardiomyocyte apoptosis (r=0 .943,p<0.001). Conclusion Ischemic pr econditioning significantly reduced PMN infiltration and attenuated myocyte apop tosis.