Background: This study aimed to investigate the relationship between the experience level of physicians who initially make a clinical diagnosis of patients with ST segment elevation myocardial infarction in the emergency department and door-to-balloon time (DBT). Material and methods: Between January and December 2018, the research group was selected randomly among 522 patients with ST elevation myocardial infarction who were immediately treated in the catheter laboratory. Angiography images were monitored from the patients’ records in the catheter laboratory. The time of admission to the emergency room was obtained using the hospital registration system. The experience level of physicians who initially clinically diagnosed patients in the emergency department was divided into three groups: medical practitioner (who did not receive emergency training), assistant physician (undergoing emergency medicine training), and emergency medicine specialist. Results: The study included 522 patients who underwent primary percutaneous intervention due to ST segment elevation myocardial infarction. The mean age was lower, and cardiogenic shock and mortality rates were lower in the group with DBT<60 /min compared with the group with DBT>60/min. In the expert group, the mean DBT was lower, but the cardiogenic shock and mortality rates were higher (p<0.05). Conclusions: The duration of DBT decreases as the experience level of the emergency physician increases, but randomization is required to determine its clinical benefit