A universal animal model has not yet been accepted in assessing prosthetic aortic valve replacement (AVR). We modified previously reported chronic ovine models used for orthotopic implantation in AVR to conduct preclinical aortic valve evaluation and to establish a predictive animal model for safety, hemodynamics, pathology and handling. Fourteen sheep underwent AVR during cardiopulmonary bypass. Hemodynamic and laboratory data as well as aortography were obtained intraoperatively and after 20 weeks of follow up. There were two operative deaths, and one sheep died before scheduled termination. Gross pathology of the implanted valve revealed no abnormalities.