Following reports of accelerated wear in the model 104 Beall prosthetic valve, the authors initiated a recall and prospective follow-up study of patients who received Beall valves. In the 3 years of the follow-up program, 12 patients who had an isolated Beall mitral valve implanted have had elective replacement of the prosthesis. Cinefluoroscopy was the most accurate preoperative method of predicting the degree of pathologic wear. The serum lactic dehydrogenase value was the next most helpful measurement. Change in functional class, mitral regurgitation murmur, hemodynamic status, echocardiography and the duration of the valve in situ were not sensitive indicators.