Aim: The most significant clinical association of interatrial block (IAB) was found with increased risk ofatrial fibrillation and ischemic stroke. In this study, we sought to evaluate P wave duration andinteratrial block in patients presented with acute ST-segment-elevation myocardial infarction (STEMI)who underwent primary percutaneous coronary intervention (PCI).Materials and Methods: We performed a retrospective analysis of patients presented with acuteSTEMI who underwent emergent PCI. Follow-up electrocardiograms were obtained from electronicdatabase system. Echocardiographic data were also obtained from electronic patient records.Electrocardiographic measurements were performed using SEMA Workstation 3.8.1 (Schiller AG).Results: Primary analysis included 200 consecutive patients with STEMI. However, there were 20 inhospital deaths and 83 patients were lost to follow-up. Remaining 97 patients (80 male, 17 female)were included in the final analysis. Mean age was 57.0212.18 years. There were 48 patients withanterior STEMI and 49 patients with inferior STEMI. Mean duration of follow-up was 11 months andECGs at the end of the follow up revealed that the frequency of partial and advanced IAB were 13.2%and 7.7% respectively. Statistical analysis showed that neither P wave duration nor IAB showedsignificant association with the infarct related artery lesion localization. Also, the degree of systolicdysfunction was not associated with IAB. Only male gender and left atrial diameter had significantpositive correlation with P wave duration.Conclusion: IAB was not rare in patients with a history of acute coronary syndrome. The infarctrelated artery does not seem to have a significant correlation with interatrial conduction.