Acute coronary syndrome occurred in 2 young adults who had a history of Kawasaki disease (KD), but few other coronary risk factors. The first patient was a 27-year-old male with acute myocardial infarction without stenosis detected by coronary arteriography 4 years earlier. Emergency coronary arteriography showed occlusion of the right coronary artery. Aspiration-thrombectomy and rescue balloon angioplasty were successfully performed. The second patient was a 32-year-old male with unstable angina. Right coronary arteriography showed total occlusion with severe calcification. Left coronary arteriography showed 99% stenosis at the proximal site of the circumflex artery, and a directional coronary atherectomy was performed. Histological examination of a specimen from this site revealed a lipid core, macrophages, and smooth muscle cells. Restenosis was not observed on follow-up coronary arteriography after 5-6 months in either case. The coronary stenosis in each case was probably caused by accelerated atherosclerosis at the site without aneurysm as it seemed to be 'normal' on arteriography. Conventional catheter intervention was effective treatment. The sequelae of KD should be recognized as independent coronary risk factors.