Kawasaki disease is an acute, febrile, systemic syndrome of unknown etiology which principally affects young children. We present a five-year-old boy, who developed an unusual finding, acute hydrops of the gallbladder, in addition to the characteristic signs and symptoms of Kawasaki disease. Clinical features of the disease and treatment regimens, including early administration of intravenous gamma globulin (IVGG), which prevents cardiac complications, are discussed.