We experienced a case of 34-year-old male with old myocardial infarction, which seemed to be caused by spontaneous dissection of the left circumflex coronary artery, and associated papillary muscle disfunction with resultant significant mitral regurgitation. He was treated surgically by coronary artery bypass grafting and mitral valvuloplasty. Ungraftable circumflex was abandoned; instead, pediculated graft of the right gastroepiploic artery was anastomosed to the mid-portion of the right coronary artery, which also had been spontaneously dissected. Mitral regurgitation was treated with Reed's plasty of the posterior commissure and the ring annuloplasty using Carpentier-Edwards Ring. His postoperative course has been smooth and uneventful. According to the English literature of the Western hemisphere, spontaneous coronary arterial dissection usually occurs in relatively young people with a striking predilection for women, and nearly all report deal only with the coronary abnormality. To our knowledge, this is the first report of a surgical case of the spontaneous coronary dissection associated with significant mitral regurgitation.