Stunned myocardium is defined as postischemic dysfunction of viable myocardium. This phenomenon was initially described in animal models of brief ischemia followed by reperfusion, but is becoming increasingly recognized in clinical situations. One of these situations is ventricular dysfunction following coronary artery bypass surgery. Several clinical reports have demonstrated depressed ventricular function in the initial hours after coronary artery bypass surgery: this dysfunction is usually resolved within 24 to 48 hours, and does not appear to be dependent upon alterations in preload, afterload, or temperature. New therapies for improving postischemic myocardial function following cardiopulmonary bypass are under investigation.