Prosthetic heart valves (PHV) with various types and materials have been developed and used until now, but PHVs have various problems that need improving. A new type of polymer PHV have been developed to ameliorate these problems. A hydrodynamic tester has also been developed for the precise evaluation of hydrodynamic performance of the developed PHV. PHV are composed of polyurethane, a material commonly used in biomedical materials because of its good biocompatibility and mechanical properties. To investigate its hydrodynamic properties, a trileaflet and bileaflet type polymer valve was fabricated. The results of comparative tests with the 2 polymer valves and a mechanical valve showed that the trileaflet polymer valve had a better hydrodynamic performance than the others. Though the bileaflet polymer valve showed a higher pressure drop and regurgitation than the trileaflet valve due to thicker leaflet flection of the bileaflet valve, if its fabrication method and design were corrected, a better result could be expected. For a study of the long-term stability of the PHV, accelerated endurance tests and stress analysis of PHVs are needed.