Objectives: Time to reperfusion for patients with ST-segment elevation myocardial infarction (STEMI) consistently predicts mortality for fibrinolytic therapy, and the relationship between mortality and time to reperfusion with primary PCI was investigated. In contrast, studies have found conflicting results regarding the relationship between mortality and time to presentation with STEMI. We sought to determine the effect of symptom-to door time on mortality for patients with STEMI in KAMI registry. Methods: We studied a 2423 STEMI patients within 30 days of presentation and a 1478 STEMI patients treated with PCI within 12 hours of presentation at 41 hospitals participated in the KAMI registry from November 2005 to July 2006. We used hierarchical models to evaluate the effect of symptom-to-door time on in-hospital mortality adjusted for the patient characteristics in the different subgroups of patients based on symptom onset-to-door time and baseline risk status. Results: Symptom-to-door time was not associated with in-hospital mortality (mortality rate of 5.9%, 4.9%, 5.6%, 5.7% for symptom-to-door times of 90 ��� min, 91 to 180 min, 181 to 360 min, and 6 to 12 hrs, respectively). Mean symptom-to-door time was 762 min in STEMI and 540 min in primary PCI patients. In subgroup analysis, younger age (<65 yrs, 659 versus 868 min, p=0.014), male gender (697 versus 927 min, p=0.034) were presented earlier and showed lower mortality (p<0.0001 respectively) than older age and female gender. Pre-hospital ECG and vehicle with 119 call were not associated with early presentation. Conclusions: Symptom-to-door time is not associated with mortality risk, but the late presentation of older age and female gender might be associated with higher mortality. Effect of symptom-to-door time on the long-term mortality should be evaluated through the further study.