Kawasaki Disease (KD) is an acute systemic vasculitis of unknown cause . The illness is self-limited and resolves in 6 to 8 weeks. Without treatment ,however, approximately 20% to25% of children will develop cardiac sequelae . Damage to the blood vessels that supply the heart muscle (the coronary arteries ) and damage to the heart muscle itself can occur . The most common sequel is ectasia (dilation) of the coronary arteries ,or aneurysm formation . Infant younger than 1 year of age are at the greatest risk for heart involvement . Recent data have suggested that children order than 5 year of age also at increased risk of developing coronary sequelae , perhars because KD is often not suspected in older children, which leads to delayed diagnosis and treatment. KD has become and leading cause of acquired heart disease in children in the United States.