Data of 401 patients who underwent mitral valve replacement with the Carpentier-Edwards Perimount bioprosthesis between 1984 and 2009 were evaluated. Their mean age was 68.1 ± 10.4 years (range, 22-90 years) and 54.9% were female. The most common etiology was degenerative disease (33.2%) and 62.1% of patients had mitral insufficiency. Follow-up was 3,178 patient-years, and 96.8% complete; the mean follow-up was 8.9 ± 3.1 years. Overall survival at 25 years was 10.2% ± 3%. Late mortality was 2.48% per patient-year, and valve-related deaths occurred at 1.62% per patient-year. The actuarial freedom from reoperation due to structural valve deterioration at 20 years was 24.3% ± 2% for degenerative disease and 15% ± 1.4% for non-degenerative disease. For degenerative valve disease, the freedom from structural valve deterioration at 18-years was 39% ± 1% for recipients <60-years old and 66% ± 2% for those ≥60-years old. Our data confirm the excellent durability and low mortality associated with the Carpentier-Edwards Perimount for mitral valve replacement. The rate of calcification of the valve was unrelated to degenerative valve disease, but our findings suggest that this prosthesis gives better results in recipients ≥60-years old than in younger patients.