We report the case of a patient with a pseudoaneurysm of the left coronary ostial anastomoses diagnosed 6 years after a Bentall procedure with coronary button anastomoses had been performed. Preoperatively, the pseudoaneurysm of the ascending aorta was diagnosed by transesophageal echocardiography and multislice tomography, and the diagnosis was confirmed by surgery. Intraoperatively, the dehiscence of the button anastomosis of the left coronary artery was determined. The operative technique for the repair of the left coronary anastomosis dehiscence was direct closure through a sternotomy using extracorporeal circulation. The patient was discharged on the twelfth day without problems. In conclusion, we demonstrated that the patient with a pseudoaneurysm after a conduit operation of the ascending aorta can be prediagnosed by using echocardiography and multislice tomography.