Abstract: Objective: To analyze the relationship between U wave inversion and coronary lesions in patients with acute coronary syndrome. Methods: Eighty-six ACS patients diagnosed by coronary angiography were divided into the U wave inversion group and non-U wave inversion group according to the U wave of electrocardiogram. The index of different coronary artery lesions between the two groups were compared. Results: The U wave inversion in 38 cases and non-U wave inversion in 48 cases were identified. The incidence of UA and ST segment elevation myocardial infarction in non-U wave inversion group were significantly more and less than those in U wave inversion group, respectively(P<0.01). Compared with non-U wave inversion group, the value of E/A and LVEF in U wave inversion group decreased(P<0.01). U wave inversion group was mainly characterized by moderate and severe stenosis, no obvious lesion and mild stenosis in non-U wave inversion group were identified, and the differences of those were statistically significant(P<0.01). The difference of the surface morphology of coronary lesions between two groups was statistically significant(P<0.01). The incidence in left main(LM) and left anterior descending(LAD) in U wave inversion group were higher than those in non-U wave inversion group(P<0.01), and the differences of the incidence of left circumflex and right coronary artery(RCA) between two groups were not statistically significant(P>0.05). The differences of the incidence of the single, double and three lesions vessels between two groups were statistically significant(P<0.01). The differences of the incidence of U wave inversion depth, coronary lesion vessels and degree of stenosis between two groups were statistically significant(P<0.01), the difference of the surface morphology of coronary lesions between two groups was not statistically significant(P>0.01). Conclusions: ECG U wave inversion in patients with ACS can effectively reflect the severity of coronary lesions.