We report an unusual case of cerebral embolization that occurred after intravenous thrombolytic therapy for myocardial infarction. Direct observation by serial echocardiograms in this patient confirmed that the thrombolytic treatment induced lysis and fragmentation of thrombus, and the subsequent dislodging and embolization of preexisting cardiac thrombi, which caused the cerebral infarction. It is suggested that an echocardiogram, if instantly available, be performed before considering thrombolytic therapy whenever acute anterior wall myocardial infarction is impressed.