We report a case of Marfan's syndrome in a patient who, 20 months after undergoing Cabrol's operation, underwent beating coronary artery bypass grafting without the aid of cardiopulmonary bypass for ostial stenosis of the left main coronary artery after acute myocardial infarction was diagnosed. The patient was a 31-year-old woman who had undergone Cabrol's operation for annulo-aortic ectasia at 29 years of age, and whose course thereafter was uneventful. On May 26, 2000, she complained of chest pain, and was admitted to our hospital with a diagnosis of acute myocardial infarction. On June 17 of the same year, a 90% ostial stenosis of the left main coronary artery was detected by coronary angiography. She subsequently underwent beating coronary artery bypass grafting without the aid of cardiopulmonary bypass, using left internal thoracic artery (LITA) anastomosis to the left anterior descending artery (LAD) via median sternotomy. The LAD was so much displaced laterally and pericardial adhesion was so dense on the apical aspect that good visualization of the LAD could not be obtained by the conventional percardiotomy. Therefore, the pericardium over the contemplated LAD anastomosis was resected circularly, and the LITA was anastomosed to the LAD through the pericardial opening. Postoperative angiography showed a widely patent LITA, although the stenotic lesion of the left main coronary ostium was totally occluded.