Abstract: To investigate the clinical influence of ischemia preconditioning to acute myocardial infarction, 78 patients with acute myocardial infarction were divided into two groups (IP and P) based onwhether they had angina of myocardial ischemia before AMI or not - The average value of the peak of myocardial enzyme and the incidence of abnormal Q wave, left ventricular failure and disrhythmia were compared between IP and P groups. In group IP the incidence (70 % ) of NQMI was much higher than that ingroup P (18. 75 % ), and in general the clinical manifestations were more moderate than those in group P.There are two aspects showing the effect of ischemia preconditioning on AMI: to restrict the area extensionof AMI and to modify the clinical process of AMI.