Administration of thrombolytic agents to patients with misdiagnosis of acute myocardial infarction can result in serious side effects. A case of aortic dissection that was misdiagnosed as acute myocardial infarction and received rtPA is reported. Within 1 hour of rtPA infusion, the patient developed cardiac tamponade. Type 1 aortic dissection was diagnosed by aortic angiogram. The patient underwent emergency resection of the dissection and evacuation of the pericardial and anterior mediastinal hematoma. Although he required massive transfusion of blood products intraoperatively, he is doing well 22 months after his surgery.