Abstract Background Real-world data on baseline characteristics, clinical practice, and outcomes of late presentation (12 to 48 h of symptom onset) in patients with ST-segment elevation myocardial infarction (STEMI) are limited. Objectives This study aimed to investigate real-world features of STEMI late presenters in the contemporary percutaneous coronary intervention (PCI) era. Methods Of 13,707 patients from the Korea Acute Myocardial Infarction Registry-National Institutes of Health database, 5,826 consecutive patients diagnosed with STEMI within 48 h of symptom onset during 2011 to 2015 were categorized as late (12 to 48 h; n = 624) or early ( Results Late presenters had remarkably worse clinical outcomes than early presenters (180-day mortality: 10.7% vs. 6.8%; 3-year mortality: 16.2% vs. 10.6%; both log-rank p Conclusions Data from a nationwide prospective Korean registry reveal that inverse steep differences in the use of invasive interventional procedures and mortality rates were found between early and late presenters after STEMI. A multidisciplinary approach is required in identifying late presenters of STEMI who can benefit from invasive interventional procedures until further studied.