Although a general consensus on the etiology of Kawasaki syndrome has not been reached, increasing evidence suggests that this illness represents a response to a superantigen. This conclusion is based on the observations of the immunologic changes that characterize the acute stages of illness as well as on the demonstrated association with toxin-producing bacteria in the pharynx and gastrointestinal tract. Therapy with intravenous gamma globulin and high-dose aspirin remains the standard of care for acute disease. Long-term follow-up of increasing numbers of children has confirmed that few properly treated children are at risk for the development of coronary artery abnormalities due to this illness.