Background and Objectives: The aim of this study is to identify the extent of initial malapposition using optical coherence tomography (OCT) in ST-elevation myocardial infarctions (STEMI) treated with drug-eluting stents (DES) and to compare the results for different types of stents. Materials and Methods: A total of 19 patients diagnosed with STEMI who underwent primary percutaneous coronary intervention (PCI) were enrolled in this study. The OCT was performed within 72 hours after the primary PCI. Distances between the endo-luminal surface of the strut reflection and the vessel wall and the extent of malapposition between different stents were measured and analyzed. Results: Sirolimus-eluting stents (SES) were deployed in 5 patients (26%), paclitaxel-eluting stents (PES) were deployed in 6 patients (32%), and zotarolimus-eluting stents (ZES) were deployed in 8 patients (42%). In total, 4162 struts in 451 mm single-stent segments were analyzed. Of these stents, 1237 struts in SES, 1325 in PES, and 1600 in ZES were analyzed and distances between the endo-luminal surface of the strut reflection and the vessel wall were found to be significantly different (140짹56 關m in SES, 88짹29 關m in PES and 77짹27 in ZES, p=0.001) and the numbers of malapposition struts were also significantly different (405 (33%) in SES, 136 (10%) in PES, 159 (10%) in ZES, p=0.001). Conclusion: OCT is a powerful tool for detecting malapposition in STEMI performing primary PCI treated with DES. SES has higher rates of malapposition than other DES in this group