Kawasaki disease (KD) is a vasculitis syndrome of unspecified etiology that usually occurs in childhood. Although KD is self-limited disease, KD patients can have coronary artery aneurysms, which can develop to myocardial infarction and myocardial infarction is the main cause of KD mortality. But treatment strategy is controversial. A 21-year-old man with no preivious medical history presented with chest pain that were ongoing for 3 hours. On presentation, he was stable hemodynamically, afebrile, and had a benign physical exam. Initial ECG showed ST elevation in II, III, aVF leads. Initial laboratory data revealed a CK-MB of 1.25 mg/dL and a Troponin-T of 0.010 mg/dL, and a normal complete blood count (CBC) and coagulation study. The patient was taken for emergent cardiac angiography within 1 hour of presentation, which revealed marked aneurysmal dilatation (17×34mm) of the proximal RCA with eggshell calcification and total occlusion with much thrombi in the aneurysm. We decided to inject intravenous tenecteplase (tPA) 0.5 mg/kg bolus because of thrombus burden. Follow up coronay angiography after 7 days showed TIMI 3 flow(+) and proximal aneurysmal dilatation(+). He was discharged from the hospital on warfarin therapy. At follow-up, the patient had returned to full activities and had remained asymptomatic. Missed `Kawasaki disease`` in childhood can present with ST elevation myocardial infarction in adulthood. For these patients with large thrombus burden, systemic tenecteplase can be effect to revasculize occluded coronay arteries.