SUMMARYThe ECG is a test that is used frequently in the acute setting. It has a significant impact on decisions regarding patient discharge and further investigations. On a single day in the ambulatory emergency care setting two patients presented with chest pain. The ECG findings were abnormal, but also out of context with the clinical findings. On close inspection of the ECG machine it was identified that although all leads attached to the patient were in the correct position, the two cables connecting the leads to the machine had been reversed. Had the error not been discovered promptly there was the potential that further, more harmful investigations would have been performed. These cases highlight that although the ECG is a simple and non-invasive investigation it should be an adjunct to clinical working diagnosis. BACKGROUND