INTRODUCTION: The aim of the ST SMART trial is to determine whether prehospital ST monitoring with telephone transmission to the target hospital will improve hospital time to treatment in acute coronary syndromes. The present analysis reports results of the feasibility pilot study. METHODS: All patients calling 911 for chest pain in Santa Cruz County California were monitored with a synthesized 12-lead ECG. Prehospital ECGs were printed for clinical use in the experimental group; control group patient care used only ECGs recorded after hospital arrival. RESULTS: Five patients with non-ST elevation myocardial infarction or unstable angina had normal ECGs upon hospital arrival but evidence of ischemia in their prehospital ECGs. Three patients with ST elevation myocardial infarction were treated with primary percutaneous coronary intervention, with "door to balloon" times of 47 and 65 minutes in 2 experimental group patients and 148 minutes in the one control group patient. CONCLUSION: Prehospital ST monitoring appears feasible. Its potential to improve hospital time to diagnosis and treatment in acute coronary syndromes, and the clinical benefits of such improvement will be studied in the larger, ongoing ST SMART trial.