Formation of coronary aneurysms is often seen on the patients in the acute phase of Kawasaki disease by echocardiography, and after the convalescent phase, some patients show disappearance of aneurysms but some of them show combining stenotic lesions at inlets and/or outlets of aneurysms on coronary arteriography. According to follow-up studies of coronary arterial lesions, the degree of stenosis quite frequently increases and progresses over a period up to 10 years or more after the onset of the disease. The severe stenosis appears the most frequently at the proximal portion of the left anterior descending artery and secondly at the main trunk of the main coronary artery. They die suddenly or suffer from severe myocardial infarction unless they are treated with aortocoronary bypass surgery. However, it is rare to have symptoms of ischemic heart disease even in patients with severe obstructive lesions. In fact, the sensitivity of exercise testing in diagnosis of myocardial ischemia is very low. Dipyridamole thallium myocardial imaging is reasonably useful, but dipyridamole can he dangerous when it is given without the precise information of the patient's stenosis. Coronary arteriography is, therefore, essential not only to determine the appropriate treatment of the c ronary arterial lesions but also for follow-up. According to the histopathologic study, even the patients in whom coronary arterial lesions were not visualized on coronary arteriography often show some intimal proliferation. These patients may well present a problem in the future due to the sequels of angiitis. Because of this, continuous regular follow-up should be necessary, even in patients with no evidence of coronary arterial lesion.