Abstract. ECG has been somewhat neglected in clinical decision making in the era of high technology. During the last few years it has become evident that there is an urgent need for simple, cheap and universally available tools for clinical decision making in acute coronary syndromes. In the acute phase risk stratification is largely based on simple clinical parameters, laboratory markers of myocardial injury and 12(-15) lead ECG. Because important therapeutic decisions are made during the first few hours after initiation of chest pain, when troponin levels are not elevated, ECG is of crucial importance. It is important to register an ECG during an episode of anginal pain. As ECG changes are very dynamic, ECG may be normal between episodes of pain. The ECG during the obstructive phase provides important anatomical and physiological information about the coronary arteries. During the presentation cases from our hospital will be described to show how we try to optimize the information in the ECG registered during pain in clinical decision-making. We will present cases to show what conclusions we think can be drawn from the ECG about the culprit artery, the level of obstruction and dimension of the artery by defining the core of ischaemia, reciprocal changes and the attenuation phenomenon. Also the grade of ischaemia, signs of myocardial reperfusion and different types of ischaemia in cases without ST-segment elevation will be covered briefly. The examples will show how ECG helps in optimizing risk stratification of individual patients to decide what type of therapy to choose and how urgently the patient should be evaluated invasively. In our country we have a long way to go before we can take all patients with high-risk markers for immediate invasive evaluation. Probably this is the case also in many other countries. This emphasizes the need for important clinical tools like ECG.