Abstract: Objective: To explore the value of the ST-segment elevation in lead avR of treadmill exercise test in the diagnosis of left coronary artery lesions. Methods: Eighty-two coronary artery disease patients with the positive treadmill exercise test were divided into the ST-segment elevation group(42 cases) and non-ST-segment elevation group(40 cases) according to the ST-segment elevation(≥ 0.01 mV).The coronary angiography(CAG) in two groups was examined. Results: Three cases of negative CAG and 39 cases of positive CAG in ST-segment elevation group,and 4 cases of negative CAG and 36 cases of positive CAG in non-ST-segment elevation group were identified.The incidence rate of proximal left anterior lesion in ST-segment elevation group(58.97%) was higher than that in non-ST-segment elevation group(33.33%)(P<0.05),but the incidence rate of distal left anterior lesion in ST-segment elevation group(5.13%) was lower than that in non-ST-segment elevation group(50.00%)(P<0.01).The differences of the incidence rates of left main branch,right coronary artery and three-branch lesions between two groups were not statistically significant(P>0.05).The positive predictive value of left main branch lesion was 70.00% under the condition of positive ST-elevation in lead avR,and the positive predictive value was 90.91% under the condition of combination of left main branch with proximal left anterior branch. Conclusions: The positive treadmill exercise test combined with ST-segment elevation ≥ 0.01 mV in lead avR has high diagnostic values in left coronary artery lesions.