In this study we have examined the ability of senior house officers in the Accident and Emergency (A&E) Department to interpret electrocardiographs (ECGs) and tested the value of a single seminar and guidelines on interpretation. We prospectively audited ECG interpretation taken from notes over a two-month period and repeated this audit following a single seminar by a consultant cardiologist and after the issue of guidelines. A formal test of interpretation of a set of 20 ECGs by senior house officers in A&E was also carried out. 245 case notes were reviewed and in one third the ECG was interpreted incorrectly by senior house officers in A&E but incorrect clinical management followed in only 3.2% of cases. Following the intervention, 242 case notes were reviewed and serious misinterpretations were halved as was the number of patients mismanaged as a result (1.7%). In conclusion, formal training in ECG interpretation can reduce serious errors.