Over a 25-year period, we encountered 12 patients who died suddenly with coronary arterial lesions due to Kawasaki disease. We report their clinical course, and analyze the happenings of their deaths. Of the 12 patients, 10 were dead on arrival at hospital. Their age at death ranged from 13 months to 27 years, with a median of 16 years, and the interval from the onset of Kawasaki disease to death ranged from 2 months to 24 years. In 4 patients, death was found to be due to myocardial infarction, while in the remaining 8, it could not be determined. In 7 patients, coronary angiograms obtained less than 4 months after the acute onset of Kawasaki disease showed lesions bilaterally, most being giant aneurysms. Myocardial infarction had occurred in 6 patients prior to their death. In 1 patient of the late 1970s, who collapsed after running, cardiac sequels had not been suspected prior to autopsy. During the 1980s, 3 infants with bilateral giant aneurysms died within a year of the initial onset of Kawasaki disease, with acute myocardial infarction being the cause in 2 of them. In the late 1990s, and the 2000s, 5 patients died suddenly with left ventricular dysfunction, their ejection fractions being less than 40 percent more than 20 years after the initial onset of Kawasaki disease. Prior to their sudden deaths, they had had no cardiac events for many years, but had suffered previous myocardial infarctions. Multifocal premature ventricular contractions, and non-sustained ventricular tachycardia, are probable risk factors in such patients. Careful follow-up, checking for ventricular arrhythmia, is needed to prevent sudden death in patients suffering left ventricular dysfunction in the setting of Kawasaki disease.