The benefits of establishing early coronary reperfusion in acute myocardial infarction (MI) have now been unequivocally established. However, current pharmacologic strategies fail to achieve effective reperfusion in 30 percent or more of patients, and many patients with occluded infarct arteries do not meet current criteria for use of these agents. Early angioplasty, an effective reperfusion method, is available to a small proportion of potentially eligible US acute MI patients. Hence a substantial number of acute MI patients pass the time when reperfusion therapy has any documented benefit (12 - 24 hours) with a persistently closed infarct vessel. Several lines of experimental and clinical evidence suggest that late reperfusion of these patients could provide clinically significant reductions in mortality and morbidity.