Percutaneous revascularization of coronary arteries with intraluminal thrombi is a clinical problem. We report a patient in whom we administered prolonged infusion of intracoronary urokinase and then assessed the stenosis with intravascular ultrasound before and after atherectomy. We found both angiography and intravascular ultrasound to be misleading in determining the presence of residual thrombus after thrombolysis.