The author has involved in two types of clinically available artificial hearts in Japan for these 30 years. Firstly, Toyobo auxiliary pulsatile ventricular assist pump was commercialized in 1991 and over 700 clinical cases are reported in Japanese market. Secondly, an implantable non-pulsatile ventricular assist pump (EVAHEART, Sunmedical Tech. Res. Co.) has been implanted into 11 patients in Japan. The author has been establishing a methodology to eliminate considerable risk factors through a development of hydrodynamic performance test, durability test and biocompatibility test. These in vitro tests are all effective to ensure a safety of the system and also in vitro tests have a contribution to reduce a number of animal experiments.