Thrombotic obstruction of prosthetic valves is a serious problem. Early diagnosis and prompt treatment are life-saving in these cases. Three patients presented with subacute and chronic symptoms of prosthetic valve thrombosis of varying duration (7 days to 2 years). All 3 had a Medtronic Hall tilting disc valve implanted in a previous operation in the aortic or mitral position. Diagnosis was established by 2-dimensional echocardiography. Under cardiopulmonary or femorofemoral bypass, thrombectomy and rotation of the disc within the valve housing were performed through a median sternotomy. All the patients had an uncomplicated postoperative course. Pressure gradients fell markedly at discharge 8 to 10 days after surgery. The patients were followed up for between 3 and 11 months, during which they showed excellent prosthetic valve function and reduced gradients. The ability to rotate the valve within the housing allows adequate thrombectomy and pannus excision. Even several years after implantation (more than 10 years in 2 cases), the valve could still be rotated readily to obtain optimum flow and low pressure gradients.