Background: In patients with ST-segment elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (PCI), early reperfusion is believed to improve left ventricular systolic function and reduce mortality. However, long-term (>1 year) data are sparse. The purpose of this study was to evaluate the association of symptom onset-to-door time (OTD) and door-to-balloon time (DTB) with primary PCI with one-year mortality and clinical outcomes. Methods: A cohort of 4,564 consecutive patients (median age 63 years, 73% male) with STEMI treated with primary PCI were selected from a prospective cohort study, the Korea Acute Myocardial Infarction Registry (KAMIR) from November 2005 through January 2008, and stratified according to OTD and DTB and analyzed, including multivariable modeling for death and composite of major adverse cardiac events (MACE, death or myocardial infarction or revascularization) during in-hospital period and at one-year. Results: Primary PCI was performed at a median OTD of 160 minutes (range, 16 - 720) and a median DTB of 82 minutes (range, 16 - 360) after presentation. Among the quintiles of OTD (<90 min, 90-180 min, 180-270 min, 270-360 min, and 360-720 min), there was significant difference in crude in-hospital death and composite of MACE (4.7%, 4.4%, 5.4%, 5.2%, and 7.1%, p = 0.036; 5.2%, 5.0%, 6.1%, 6.4%, and 7.5%, p = 0.035, respectively) and crude one-year death and composite of MACE (6.4%, 6.5%, 7.3%, 9.6%, and 12.0%, p <0.001; 14.0%, 13.9%, 15.0%, 16.7%, and 18.2%, p = 0.012, respectively). Among the quintiles of DTB (<60 min, 60-90 min, 90-120 min, 120-180 min, and 180-360 min), there was significant difference only in crude one-year death (6.4%, 7.9%, 9.6%, 8.6%, and 9.2%, p = 0.024). In a multivariable modeling, OTD was identified as an independent predictor of one-year mortality (OR 1.185, 95% CI 1.061-1.324, p = 0.0027) and DTB was marginally significant as a predictor of one-year mortality (OR 1.113, 95% CI 0.987-1.256, p = 0.0814). Conclusions: This study demonstrated that both OTD and DTB were significantly associated with increased one-year mortality after primary PCI in patients with STEMI. Physicians and health care systems as well as the community should work together to minimize both OTD and DTB.