Kawasaki syndrome (KS) is an acute, febrile, self-limited, multisystem vasculitis that almost exclusively affects young children. First described in 1967 by Dr. Tomisaku Kawasaki of Tokyo, Japan, it now has been recognized as occurring in all regions of the world among children of multiple and diverse ethnic groups. Its occurrence is common enough in all parts of North America that primary physicians should be familiar with its diagnosis and treatment. Originally thought to be a benign febrile exanthem, it soon was recognized that fever could be prolonged and that significant adverse cardiac effects were common, especially the development of coronary aneurysms that could lead to myocardial infarction and sudden death. Fatal KS is a multisystem vasculitis indistinguishable from infantile periarteritis nodosa (IPN); until the discovery of KS, IPN had been a condition diagnosed only at autopsy. Dr. Kawasaki's enduring contribution is the recognition and description of the major clinical features of this unique disease, which only rarely causes death. The clinical criteria he described remain the basis of all clinical and epidemiologic descriptions in use today. Although effective therapy has been discovered, the etiology of the disease remains unknown. The acute, febrile, self-limited nature of the disease and its clinical features of fever; rash; and menigeal, joint, hepatic, and mucous membrane inflammation strongly suggest that the etiologic agent is microbial.