Kawasaki disease, also known as mucocutaneous lymph node syndrome, was first described in Japan in 1967. It is currently the leading cause of acquired heart disease in children in the United States. Untreated Kawasaki disease may lead to the formation of coronary artery aneurysms and sudden cardiac death in children. This vasculitis presents with fever for ≥ 5 days, plus a combination of key criteria. Because each of the symptoms commonly occurs in other childhood illnesses, the disease can be difficult to diagnose, especially in children who present with an incomplete form of the disease. At this time, the etiology of the disease remains unknown, and there is no single diagnostic test to confirm the diagnosis. This issue reviews the presentation, diagnostic criteria, and management of Kawasaki disease in the emergency department. Emergency clinicians should consider Kawasaki disease as a diagnosis in pediatric patients presenting with prolonged fever, as prompt evaluation and management can significantly decrease the risk of serious cardiac sequelae.