OBJECTIVES:  The prompt treatment of ST segment elevation myocardial infarction (STEMI) is associated with conservation of cardiac function and reduced mortality. Acquisition of pre-hospital electrocardiogram (ECG) by first responders and digital transmission of the ECG to the hospital has been identified as a strategy to reduce time to treatment to the recommended 90 minutes. The purpose of this study was to summarize the literature on the difference between patients with pre-hospital ECG to patients with in-hospital ECG.   METHODS:  This systematic review of MEDLINE indexed articles used the terms Dyspnea [MeSH] OR Chest Pain [MeSH] OR Myocardial Infarction/therapy [MAJR] with Time Factor [MeSH] and Comparative Study [pub type].  Study inclusions were: English, human, publication between January 1, 2002 to November 30, 2012. Case reports, letters, news articles and reviews were excluded.  Comparative studies which included a group with pre-hospital ECG with transmission to the hospital and a control group of patients with in-hospital ECG were eligible for inclusion. The data outcomes extracted included patient characteristics, onset to treatment (OTT) and door to treatment time (DTT). RESULTS:  The search found 1029 articles, 8 passed two-tiered screening and were extracted. Three studies described thrombolysis, six studies described angioplasty (one study included both treatments). Four studies reported OTT, the pre-hospital ECG group had statistically significant shorter times (range 64-260 min pre-hospital ECG and 103-432 min in-hospital ECG). Six studies reported DTT the pre-hospital ECG group were statistically significantly shorter (range 20-100 min pre-hospital ECG group and 17-133 in-hospital ECG). Pre-hospital groups reported median DTT of < 90 minutes (range 50-66 min). CONCLUSIONS:  This review found significant beneficial differences in the onset to treatment and door to treatment times of STEMI patients with pre-hospital ECG. Transmission of pre-hospital ECG is an important component of a strategy to achieve door to treatment times of under 90 minutes.