Abstract： AIM:To investigate the relation between U wave inversion and coronary angiography(CAG)of acute coronary syndrome.METHODS:Sixty-nine patients who were diagnosed with ACS by CAG from December 2005 to May 2009.All patents underwent CAG and electrocardiographic examination.The result of CAG and the change of ECG were recorded,compared and analyzed.RESULTS:There were 30 cases of U wave inversion and 39 cases of U wave non-inversion.The incidence of UA and STEMI were higher in the U wave inversion than in U wave non-inversion (P<0.05).The left ventricular systolic function and diastolic function was also higher in the U wave inversion.The incidence of the left main coronary artery(LM)and the left anterior descending coronary artery(LAD)was higher in U wave inversion than in U wave non-inversion(P<0.05).Furthermore,the incidence of two-vessel and three-vessel coronary arteries and the stenosis of coronary artery in U wave inversion were higher than that in U wave non-inversion(P<0.05).The narrowing characteristics of coronary artery in U wave inversion were more likely to be complex lesion(P<0.05).The depth of U wave in 30 cases with U wave inversion was closely related to the number of vessel and the stenosis of coronary artery(P<0.05).CONCLUSION:U wave inversion was a predictor of the prognosis of severe degree of acute coronary syndrome.