A review of the literature revealed that 1) all prosthetic heart valves to date are plagued by certain problems, 2) all prosthetic valves in current clinical use are central-occlusion valves which do not effectively simulate natural valve action, and 3) the development of a true central-flow valve with the potential benefits of reduced pressure drop, turbulence, hemolysis, and thromboembolism could be a significant contribution. A central-flow, double-leaflet valve was developed. The wear, pressure drop, turbulence, and regurgitation associated with the new valve were evaluated. The wear test results indicated the need for additional testing using more wear resistant pin-bearing combinations. The flow tests revealed that the new valve with a 65 degree opening angle produced less pressure drop than other prostheses, but the new valve did not reduce turbulence as compared to other prostheses. In addition, the backflow and mean leak associated with the new valve were too high. Details of the testing procedures are presented and recommendations for future valve modifications and testing are included. / M.S.