Obstructive coronary disease has many clinical expressions and some are used as useful indicators of risk. Apart from symptoms, transient ischaemia occurs during daily life, is mostly silent and represents one measure of risk. Ambulatory monitoring of the electrocardiogram shows that ischaemia occurs with increased frequency during the morning hours while waking and rising. This coincides with other damaging vascular events, increased sympathetic activity and changes in coronary blood supply and myocardial oxygen demand that may favour a lower threshold to ischaemia. Calcium blockers, beta-blockers and aspirin can favourably affect this process and long-acting drugs appear to be a more rational approach given the variability of ischaemia over time.