Kawasaki disease was first reported in 1967 by Japanese pediatrician Tomisaku Kawasaki as an acute febrile syndrome mainly affecting the skin, mucosa, and lymph nodes. 1 Although initially recognized as benign, this syndrome was subsequently acknowledged to have a serious complication of coronary artery aneurysm, 2 and it has gained the worldwide interest of pediatricians and pediatric cardiologists. The importance of and interest in this disease can be seen in the existence of the unusual publication of the English translation of the first report in Japanese. 3 Because Japan is the country where the disease was first observed and the largest numbers of new patients are diagnosed each year, researchers there have been making outstanding efforts to uncover the mystery of this disease. Scientists from other countries have also contributed greatly in this regard despite the underlying difficulties in conducting research due to the limited number of cases compared with Japan. The present review article covers such longstanding efforts and their fruits, with a special focus on the long-term outcome of Kawasaki disease. Although data on the epidemiology, origin, pathophysiology, and treatment of this disease are important for a better understanding of the outcome, they have been reviewed extensively by several previous publications. 4–6 Nevertheless, key data on these topics are summarized briefly herein.