American pediatricians were able to recognize Kawasaki disease. The etiology of Kawasaki disease remains undetermined despite many trials. Epidemiological studies of a disease can provide a new understanding or insight of the pathophysiology or risk factors of Kawasaki disease. The Japanese nationwide epidemiological surveys on Kawasaki disease have been per formed biennially, and more than 300,000 patients who had Kawasaki disease as young children have been registered in the Japanese Department of Health, Labour, and Welfare since 1970. 2) Otherwise, nationwide epidemiological surveys on Kawasaki disease have been performed triennially in South Korea and Taiwan since 1994 and 1996, respectively. 3,4) The most useful method for determining the epidemiology of Kawasaki disease is the nationwide survey with wellorganized questionnaires like the ones used in South Korea and Japan. 3,5) This can provide us with data pertaining to incidences, laboratory findings, coro nary artery complication rates, etc. Therefore, we can possibly infer the pathophysiology of and risk factors for Kawasaki disease by using these data. Two most important factors for obtaining true data from nation wide surveys are the exact diagnosis of Kawasaki disease and active responses to the surveys by pediatricians who care for affected patients. However, Kawasaki disease can be erroneously diagnosed by healthcare providers (general practitioners and pediatricians) and parents of patients with Kawasaki disease in many countries, including South Korea. 6) The over and underdiagnosis of Kawasaki dis ease can significantly influence epidemiological survey data accuracy. Accurate epide miological surveys on Kawasaki disease are necessary worldwide to increase the understanding and proper management of Kawasaki disease. In South Korea and Taiwan, National Health Insurance Ser vice (NHIS) data are also utilized for epidemiological surveys on Kawasaki disease. 3,4) This is noteworthy because the NHIS