There exists a population of adults with undiagnosed coronary arterial lesions due to Kawasaki disease occurring before 1967. We report the clinical features in 6 adult males with coronary arterial lesions caused by presumed Kawasaki disease, whose dates of birth ranged from 1945 to 1963. The age of the diagnosed coronary arterial lesions due to presumed Kawasaki disease ranged from 26 to 48 years. In 4 patients, there was a history of probable Kawasaki disease. The presenting features were chest pain in 2; syncope in 1, an abnormal electrocardiogram in 2; a history of presumed Kawasaki disease in 1, and symptomatic myocardial infarction in the final patient. Coronary angiograms revealed multi-vessel disease in 5 patients, with segmental stenosis in 5, and calcified giant aneurysms in the proximal portion of the coronary arteries also in 5. Low left ventricular ejection fractions of less than 40% were found in 3. Of the patients, 3 had undergone coronary arterial bypass grafting. A defibrillator had been implanted in 2 because of rapid ventricular tachycardia with syncope induced during electrophysiologic studies. We conclude that, in patients with multi-vessel disease or left ventricular dysfunction caused by presumed Kawasaki disease, symptoms and serious cardiac events occur in adult life with the onset of ageing, although the patients had been asymptomatic for many years after the onset of Kawasaki disease itself.