A 53-year-old woman diagnosed with chronic renal failure requiring homodialysis, and Behçet's disease was found, during a regular examination, having a large protruding mobile atheroma in the ascending aorta by transthoracic echocardiography. We performed surgery to remove the atheroma and localized debridement using moderate hypothermic circulatory arrest to prevent future stroke and embolism. She had an uneventful postoperative course.