Background—Bioprostheses are widely used as an aortic valve substitute, but knowledge about prognosis is still incomplete. The purpose of this study was to provide insight into the age-related life expectancy and actual risks of reoperation and valve-related events of patients after aortic valve replacement with a porcine bioprosthesis. Methods and Results—We conducted a meta-analysis of 9 selected reports on stented porcine bioprostheses, including 5837 patients with a total follow-up of 31 874 patient-years. The annual rates of valve thrombosis, thromboembolism, hemorrhage, and nonstructural dysfunction were 0.03%, 0.87%, 0.38%, and 0.38%, respectively. The annual rate of endocarditis was estimated at 0.68 % for.6 months of implantation and was 5 times as high during the first 6 months. Structural valve deterioration was described with a Weibull model that incorporated lower risks for older patients. These estimates were used to parameterize, calibrate, and validate a mathematical microsimulation model. The model was used to predict life expectancy and actual risks of reoperation and valve-related events after implantation for patients of different ages. For a 65-year-old male, these figures were 11.3 years, 28%, and 47%, respectively. Conclusions—The combination of meta-analysis with microsimulation enabled a detailed insight into the prognosis after aortic valve replacement with a bioprosthesis for patients of different ages. This information will be useful for patient counseling and clinical decision making. It also could serve as a baseline for the evaluation of newer valve types. (Circulation. 2001;103:1535-1541.