A novel design of synthetic leaflet heart valve has been developed and evaluated. The hydrodynamic function of the polyurethane heart valve was compared with that of a porcine bioprosthesis and tilting disc mechanical heart valve of similar size. The durability characteristics of the design were also investigated. This new design of polyurethane heart valve showed improved hydrodynamic function in comparison with either the bioprosthetic or mechanical heart valve. The pulsatile flow results indicated improved potential clinical function because of a lower total energy loss associated with this valve. The durability of the novel design of polyurethane heart valve was also demonstrated, through accelerated fatigue testing to 360 million cycles, without failure.