Myocardial ischaemia is responsible for angina, unstable angina, and, less commonly, shortness of breath secondary to ischaemic left ventricular dysfunction (angina equivalent) as well as cardiac arrhythmias. This article will deal with the mechanisms of myocardial ischaemia likely to be encountered in patients presenting with the chronic coronary insufficiency and stable symptoms of angina. It will not deal with the vessel wall based mechanisms of unstable or acute coronary syndromes which are covered elsewhere in this series.