Objective To study the clinical significance of exercise- induced ST- segment elevation(STE) in patients without previous myocardial infarction(MI) Methods Ten patients without previous MI who developed STE during exercise testing were underwent coronary angiography, left ventriculography and rest electrocardiography, and Bruce protocol were used during exercise test. Results The incidence of exercise-induced STE in patients without previous MI was 0. 28 % (10/3564)One of the 10 patients had only a mild coronary lesion (stenosis ＜ 35 % in diameter) in left anterior descending artery, but she developed an acute myocardial infarction 4 weeks after coronary angiography , and the leads of myocardial infarction and the leads of exercise-induced STE elevation were same, the others all had severe coronary stenosis(90 % ～ 100 % ) . There was a good correlation between leads of ST-segment elevation and ischemic related artery. Nine patients received invasive therapy. During a period of 28months (range 8 to 48 months) of follow-up, 2 of them received PTCA again at 11 and 19 months after their discharge, prospectively. Conclusions The findings indicats ST-elevation during exercise is a specific marker of severe transmural regional ischemia and should be an indication for coronary angiography. Most patients with exercise-induced ST-segment elevation have critical organic stenosis of the ischemic- related coronary artery and are candidates for myocardial revascularization. In a few patients, ST-segment elevation during exercise may be caused by coronary artery spasm in the absence of significant organic lesions, and they may have a poor prognosis.