The benefits of thrombolytic therapy in reducing the mortality associated with acute myocardial infarction are well documented. Presumably, this is on the basis of a patent IRA, although other mechanisms may be involved. Because there is a 25% to 30% failure rate for thrombolytic therapy that is associated with a significantly worse prognosis, it is crucial to document reperfusion in a timely fashion. In cases of failure to reperfuse, the patient could be considered a candidate for secondary mechanical intervention. While coronary arteriography is presently the "gold standard" to document reperfusion, this is an invasive procedure associated with small but defined risks for the patient. A noninvasive marker that is readily available and highly accurate is most desirable. There are a number of methods currently used to document coronary reperfusion noninvasively. This review discusses the advantages and disadvantages of each method, and the need for continued evaluation and refinement in noninvasive modalities to identify patients who are candidates for further intervention.