This study aimed to assess the accuracy of current ECG criteria for locating the coronary artery principally involved in an acute myocardial infarction (AMI) in order to evaluate the merits of implementing AHA/ACC recommendations that require the culprit artery be reported on an ECG interpretation. 12 lead ECGs were recorded in ambulances on patients with a suspected acute coronary syndrome. These were retrospectively analysed along with coronary angiograms. Patients were included if they had a single vessel occlusion greater than 75%. ST amplitude, as measured by computer techniques, was used to test ECG criteria identified from the literature. The best criterion for predicting LAD occlusion had SE 74.1%, SP 96.1%. For RCA and LCx, the best results were SE 74.1%, SP 90.9% and SE 35.5%, SP 94.8% respectively. In conclusion, it is possible to identify the LAD and RCA as the culprit artery with a reasonable degree of sensitivity and specificity using current criteria.