Percutaneous coronary intervention for patients with ST-segment elevation myocardial infarction (STEMI) decreases morbidity and mortality if performed within the first 2 hours of symptom onset. However, the American College of Cardiology/American Heart Association guideline for percutaneous coronary intervention door-to-balloon time (<90 minutes) in patients with STEMI is a infrequently accomplished goal. This study enrolled 277 patients with STEMI who were self-transported or transported by emergency medical services to NorthEast Medical Center for primary percutaneous coronary intervention. This study tested the hypothesis that prehospital wireless transmission of an electrocardiogram to a cardiologist's hand-held device results in shorter emergency department door-to-reperfusion time. A comparison was made between patients whose electrocardiogram was successfully transmitted during the intervention phase with (1) patients transported by the emergency medical services in the preintervention, (2) patients self-transported in the intervention phase, and (3) patients whose wireless transmission failed in the intervention phase. During the preintervention phase (2001 to 2003), 48 patients were enrolled. During the intervention phase (2003 to 2005), the following patients were enrolled: 101 self-transported patients, 24 patients with successful electrocardiographic transmission, and 19 patients for whom transmission failed. The median door-to-reperfusion time for patients with successful electrocardiographic transmission was 50 minutes, which was significantly shorter than a preintervention time of 101 minutes (p <0.0001), an intervention phase self-transport time of 96 minutes (p <0.0001), and a failed transmission time of 78 minutes (p <0.0001). In conclusion, prehospital wireless electrocardiographic transmission to a cardiologist's hand-held device significantly decreased emergency department door-to-reperfusion time, thus achieving the American College of Cardiology/American Heart Association guideline for patients with STEMI.