From January 1981 to September 1982, 107 patients have been operated on for valve replacement with the Medtronic-Hall (M-H) prosthesis. Thirty-four of them have had multiple valve replacements and they are the subject of this paper. In 2 cases there were tricuspid replacement, and in 9 other patients some type of tricuspid annuloplasty was performed. There were 2 hospital deaths (5.8%) and one late death. No thromboembolic episodes were recorded in this series of patients. In 2 instances a periprosthetic leak was detected. One of these was in a woman with an aortic and mitral valve replacement due to bacterial endocarditis. In this patient a diastolic aortic murmur was registered 4 months after the operation without hemodynamic repercussion. The other patient had endocarditis with positive blood cultures (S. epidermidis) one year after the operation and showed severe hemodynamic deterioration. The patient was re-operated on and the mitral prosthesis was replaced by another with the same characteristics. The patient is doing well. A constant but slight degree of hemolysis was found in every patient in the group.