Kawasaki disease (KD) is an acute, febrile systemic vasculitis of an unknown etiology. KD has now surpassed rheumatic fever as the leading cause of acquired heart disease in the United States (U.S.) among children younger than 5 years. Although there has been a great deal of research into the cause of KD, there is no known etiology. The lack of a diagnostic test can result in significant delays in treatment, often resulting in cardiovascular sequelae ranging from asymptomatic coronary artery ectasis or aneurysm formation to giant coronary artery aneurysms with thrombosis, myocardial infarction, and sudden death in untreated children. Continued research is integral to the evolution of the management of patients with KD because understanding the mechanism of pathogenesis would allow the development of a diagnostic test and, therefore, more rapid and comprehensive treatment. I review these facts and the coronary affection from the diagnostic and the mechanistic standpoints.