Background: Timely performance of primary percutaneous coronary intervention (PCI) in ST-segment elevation myocardial infarction (STEMI) patients improves left ventricular function and survival. However, emergency department (ED) triage may unnecessarily delay this time-dependent treatment. We sought to determine whether direct or immediate admission of STEMI patients to catheterization laboratory (Cath Lab), bypassing the ED, is feasible and can shorten the door-to-balloon time (DTB) for primary percutaneous coronary intervention (PCI). Methods: Since January 2010, we have adopted a new system of direct or immediate Cath Lab admission for primary PCI provided patients were arrived with pre-hospital notification or electrocardiogram (ECG) and stable hemodynamically. All consecutive STEMI patients who underwent primary PCI from January 2010 through June 2010 were included for this study. Baseline clinical characteristics, time interval parameters, and angiographic and procedural characteristics were compared between patients with direct or immediate Cath Lab admission and patients with conventional ED admission. Results: Sixty-nine patients (54 male, age 61 짹 12 years) underwent primary PCI during study period. Of 69 admissions, 36 (52%) were admitted directly or immediately to the Cath Lab. There were no differences in baseline clinical characteristics between the two groups. Patients with direct or immediate Cath Lab admission had a similar median symptom-to-door time (470 vs. 487 min, p = 0.93) but significantly shorter median DTB (37 vs. 76 min, p = 0.011), a difference that was particularly pronounced during ���on-duty��� hours versus ���off-duty��� hours. (46 vs. 71 min, p = 0.041). Patients with direct or immediate Cath Lab admission achieved with an 100% rate of DTB ���90 min (vs. 85% in ED admission), a 92% rate of DTB ���60 min (vs. 3% in ED admission), and a 36% rate of DTB ���30 min (vs. 0% in ED admission). There were no significant differences in infarct size determined by peak troponin levels. In-hospital mortality was not different (1.4% vs. 2.9%, p = 0.504). Conclusions: The STEMI patients eligible for direct or immediate Cath Lab admission did not differ from patients admitted via the ED. Direct or immediate Cath Lab admission, based on pre-hospital notification or ECG and stable hemodynamics, can significantly reduce time to treatment in primary PCI and allow shorter DTB targets to be reliably achieved.