Objective To evaluate the diagnostic efficacy of BARCELONA algorithms in acute myocardial infarction complicated with complete left bundle branch block. Methods The electrocardiogram and the myocardial injury bio-markers and the coronary angiography of 136 patients with complete left bundle branch block were retrospectively analyzed. Fifty-six patients with acute ST-segment elevation myocardial infarction were selected as the observation group and 80 patients without acute myocardial infarction were selected as the control group. Results The sensitivity and specificity of BARCELONA algorithms in the diagnosis of acute ST-segment elevation myocardial infarction in the presence of left bundle branch block were 94.6%（84.2%-98.6%） and 88.8%（79.2%-94.4%）. The positive predictive value was 85.5%（73.7%-92.7%）

and the negative predictive value was 95.9%（87.8%-98.9%）.Conclusions BARCELONA algorithms has high sensitivity and specificity in the diagnosis of acute ST-segment elevation myocardial infarction in the presence of left bundle branch block.