Objective To evaluate postoperative quality of life （QOL） of patients aged over 65 after mitral valvereplacement （MVR）. Methods Ninety patients aged over 65 undergoing MVR by the same surgical group in Departmentof Cardiovascular Surgery of Anzhen Hospital were prospectively enrolled in this study. There were 62 male and 28 femalepatients with their age of 65-76 （68.6±6.8） years. There were 55 patients with hypertension，38 patients with type 2 diabetes，and all the patients had persistent atrial fibrillation. Nottingham Healthy Profile （NHP，Part I） and Duke Activity StatuIndex （DASI） were used to evaluate preoperative and postoperative QOL. According to the choice of prosthetic heart valves they received，all the patients were divided into two groups with 45 patients in each group: biological valve group and mechanical valve group. All the patients received MVR via the interatrial groove approach under general anesthesia and cardiopulmonary bypass. Mechanical valve replacement was performed using continuous suture without preserving the posterior leaflet of the mitral valve. Biological valve replacement was performed using interrupted suture and some of the posteriorleaflet of the mitral valve was routinely preserved. Patients in both groups underwent intraoperative bilateral pulmonary vein isolation and left atrial appendage ablation using a bipolar radiofrequency ablation device. The left atrial appendage was not excised or ligated. Results Postoperative QOL of all the patients was significantly better than preoperative QOL. There was no statistical difference in NHP and DASI at the 6th month after discharge between the 2 groups. But from the 1st year after discharge，QOL of the biological valve group was significantly better than that of the mechanical valve group. At the 3rd year after discharge，NHP and DASI of the mechanical valve group was not statistically different from those at the 1st year after discharge，but NHP and DASI of the biological valve group was significantly better than those at the 1st year after discharge. Conclusions QOL of elderly patients are significantly improved after MVR. Patients who receive biologicalvalve replacement may acquire better long-term QOL than patients who receive mechanical valve replacement.