Background The factors influencing the q-wave changes in V5 and V6 during anterior acute myocardial infarction (AMI) have not been thoroughly described. Methods We studied 70 patients with a first anterior AMI, in whom the electrocardiogram (ECG) showed either disappearance of the normal septal q wave (n = 24) or presence of pathological Q wave in V5 and V6 (n = 46) during follow-up. The ECG and coronary angiography findings were correlated. Results There was no difference between the 2 groups in the culprit site proximal to S1 (46% vs. 36%, P = 0.405), but the culprit site was more frequently located proximal to D1 in the group with abnormal Q wave (21% vs. 67%, P = 0.001). Patients with disappearance of the septal q wave more often had a large obtuse marginal branch (46 % vs. 22%, P = 0.037) and disappearance of the r wave in V1 (88% vs. 7%, P = 0.001). Patients with abnormal Q-wave more often had a large LAD (42% vs. 71%), small r wave or tall or wide R wave in V1 (0 % vs. 89 %, P = 0.001) and abnormal Q waves in the inferior leads (33% vs. 59%, P = 0.044). Conclusions In patients with first anterior AMI, q wave changes in V5 and V6 correlated with the morphology in V1 . Emerging abnormal Q wave in V5 / V6 predicted the culprit lesion in a large LAD proximal to D1 , but disappearance of the septal q wave could not predict the culprit lesion proximal to S1 . Background The factors influencing the q-wave changes in V5 and V6 during anterior acute myocardial infarction (AMI) have not been thoroughly described. Methods We studied 70 patients with a first anterior AMI, in whom the electrocardiogram (ECG) showed either disappearance of the The septal q wave (n = 24) or presence of pathological Q wave in V5 and V6 (n = 46) during follow-up. The ECG and coronary angiography findings were correlated. Results There was no difference between the 2 groups in the culprit but the culprit site was more frequently located proximal to D1 in the group with abnormal Q waves (21% vs. 67%, P = 0.001). Patients with proximal to S1 (46% vs. 36%, P = 0.405) disappearance of the septal q wave more often had a large obtuse marginal branch (46% vs. 22%, P = 0.037) and disappearance of the r wave in V1 (88% vs. 7%, P = 0.001). Q-wave more often had a large LAD (42% vs. 71%), small r wave or tall or wide R wave in V1 (0% vs. 89%, P = 0.001) and abnormal Q waves in the inferior leads (33% vs. 59%, P = 0.044). Conclusions In patients with first anterior AMI, q wave changes in V5 and V6 correlated with the morphology in V1. Emerging abnormal Q wave in V5 / V6 predicted the culprit lesion in a large LAD proximal to D1, but disappearance of the septal q wave could not predict the culprit lesion proximal to S1.