Abstract: Objective:To study the clinical effects of myocardial ischemic-precondition on myocardial infarction. Methods:One hundred and thirty patients were divided into two groups.Group A with myocardial ischemia or angina pectoris before myocardial infarction and group B without it.And then compare and analysis the results. Results:The myocardial infarction size,mortality rate and incidence of serious complications(such as left heart failure,cardiac arrhythmias and shock)of group A are sigificiantly lower than group B. Our data indicated that myocardial ischemic-precondition may restrict the amplification of myocardial infarction size,protect the post-infarctional cardiac function,and decrease the incidence of serious cardiac arrhythmias.