The purpose of this retrospective study was to assess the clinical performance of the Medtronic-Hall prosthesis based on a review of all valve related complications over a period of nine years. From January 1978 until December 1986, 502 prostheses were implanted in 450 patients. There were 200 aortic valve replacements, 198 mitral valve replacements and 52 double valve replacements. There were 234 associated procedures performed, the most frequent being coronary grafting in 129 patients and tricuspid annuloplasty in 35 patients. The mean age of the patients (230 men and 220 women) was 54.08 +/- 11.7 years. Preoperatively, 92.2% were in NYHA class III or IV. Early mortality was 7.1% and late mortality 16.7%. The follow-up totalled 1733 patient-years (mean 49.8 +/- 31.7 months). Over a period of nine years, the valve related complication rate was 4.4% per patient-year. Thromboembolic events occurred in 37 patients (2.1% per patient-year), anticoagulant related hemorrhage in 23 patients (1.3% per patient-year), endocarditis in 11 patients (0.6% per patient-year), perivalvular leak in six patients (0.3% per patient-year) and death and reoperation in 28 patients (1.6% per patient-year). At eight and one-half years, the survival rate was 71.28 +/- 2.7% for the whole group. The actuarial rate of patients free from all valve related complications was 75.92 +/- 2.7%, rate of freedom from thromboembolism was 86.01 +/- 2.4%, freedom from anticoagulant related hemorrhage was 92.7 +/- 1.6%, freedom from endocarditis was 97.17 +/- 0.8%, freedom from perivalvular leak was 98.27 +/- 0.7% and freedom from death and reoperation was 90.70 +/- 1.9%.(ABSTRACT TRUNCATED AT 250 WORDS)