Many of the damaging clinical features of coronary artery disease can be asymptomatic or present without warning. Active myocardial ischemia is an important functional expression of coronary atherosclerosis and underlies most of these clinical manifestations. Tests in-hospital aimed at the assessment of risk can measure the activity of myocardial ischemia but do not consider ischemia during daily life. Electrocardiographic monitoring in apparently stable ambulatory patients has shown frequent asymptomatic myocardial ischemia with many new characteristics not seen in tests performed in-hospital such as the fact that events are mostly asymptomatic, surprisingly prolonged, not related to stress and show a diurnal rhythm similar to that reported for myocardial infarction. Out-of-hospital ambulatory monitoring has shown that asymptomatic ischemia is common and overlooked in the management of apparently stable patients with coronary disease. If the activity of ischemia affects prognosis, it may not be sufficient to treat symptoms alone and new goals may be necessary that aim to control all active ischemia during daily life.