The accurate determination of reperfusion in the setting of acute myocardial infarction and the evaluation of vessel patency or reocclusion has become critical in the management of patients in the thrombolytic era. This article reviews the biological properties and potential clinical applications of the new technetium-99m-labeled perfusion agents following perfusion. Both 99mTc-Sestamibi and 99mTc-Teboroxime have unique biological properties that may permit the assessment of reperfusion and vessel patency following thrombolysis. The noninvasive evaluation of patients following acute coronary reperfusion, must occur during acute, intermediate, and predischarge phases. Serial imaging with 99mTc-Sestamibi and 99mTc-Teboroxime in combination probably will serve in the future as an important means of assessing myocardial salvage, residual viability, and vessel patency following thrombolysis.