Background: Prognosis of Kawasaki disease and its main complications, coronary artery aneurysm (CAA) and myocardial ischemia were remarkably improved by intravenous immunoglobulin (IVIG) and other additional anti-inflammatory and anti-coagulation therapy. In contrast, rupture of coronary artery aneurysm is a rare, and still definitely fatal complication. Though approximately 10 cases were reported with sporadic occurrence in every three to four years in Japan, there is no patient whose life was saved. Case report: We experienced a 5-year-old boy who had already developed left CAA of 9 mm in diameter on the 7th day from onset of fever. Despite of repeated IVIG, left CAA was rapidly expanding day by day and finally the diameter became 18mm on the 12th day. Early in the next morning, sudden cardiac arrest was noted, but resuscitation was not effective. Autopsy revealed cardiac tamponade caused by rupture of very fragile wall of huge left CAA. Discussions: After this experience, we have tried to carry patients into the intensive care unit with deep sedation, if patient’s CAA is expanding more than 10mm within 2 weeks in acute stage of Kawasaki disease. Furthermore, we also recommend use of antihypertensive drugs such as calcium channel blocker and/or beta-blockers. We also have advised to colleagues in other hospitals to try in the same way when they asked for the management of similar cases. At least three patients with huge aneurysm were survived with this method in recent reports. If patient has strong inflammation sustaining with expanding huge aneurysm, plasma exchange and all possible anti-inflammatory agents including steroid or infliximab under the percutaneous cardiopulmonary support and surgeons' stand-by until inflammation will disappear. Following repair or platy of coronary aneurysm and coronary artery bypass surgery may be considered, but possibility and results are unknown. Conclusions: Because of its rarity, it is difficult to detect exact indication of deep sedation or intensive care, however, earlier and more cautious management will be safer for ‘super-giant’ aneurysm. Concerning to the sustaining inflammation with huge aneurysm, we would like to hear advices for this strategy from cardiac surgeons and pediatric intensivists.