Excessive pannus formation after implantation of a prosthetic valve is an infrequent but serious complication. A 69-year-old woman who had received a 19-mm CarboMedics aortic valve 11 years ago was readmitted to our hospital with dyspnea and chest oppression. Cineradiography did not show the restriction of valve movement. The aortic peak pressure gradient was calculated by Doppler echocardiography to be 104 mmHg. Based on the diagnosis of stenosis of the left ventricular outflow tract, the patient underwent reoperation. At reoperation, the pannus had formed circumferentially without disturbing the movement of the leaflet. A 19-mm St. Jude Medical Regent valve was implanted after enlargement of the aortic annulus. The patient’s postoperative course was uneventful. We report this characteristic finding of pannus formation after the implantation of a CarboMedics valve in the aortic position.