The patient was a 40-year-old Japanese woman. At 37 years of age she underwent stent implantation in LAD#7 for an acute myocardial infarction. Subsequently, coronary intervention was performed four times because of occlusion of the stent. Sudden death occurred at 40 years of age due to ventricular tachycardia. Clinically, the patient had had no history of collagen disease, anti-phospholipid antibody syndrome or coagulation disorder. The autopsy revealed only very mild atherosclerotic changes in the aorta and various other organs, but concentric thickening of the intima was observed in all three branches of the coronary arteries. Also, aneurysms accompanied by calcification were observed at each of LAD #6, LCx #11 and RCA #4PD. The stent was occluded with a thrombus, and the vascular walls showed infiltration by lymphocytes, plasma cells and numerous eosinophils. The eosinophil infiltration was confined to the site of the stent. It was surmised that the patient had experienced late stent thrombosis due to a hypersensitivity reaction to the DES on the basis of a development of a state of high susceptibility to thrombus formation because of a coronary aneurysm. The aneurysm was suspected of being a post-inflammatory change of Kawasaki disease.