The biomedical properties of tantalum nitride thin films synthesized by reactive magnetron sputtering employing orthogonal design technology are investigated. The adhesion properties between the film and substrate can be enhanced by optimizing the sputtering gas pressure and substrate temperature. The hardness of the tantalum nitride films is greatly affected by the nitrogen partial pressure, and our results show that films deposited under the optimal conditions can achieve a hardness value of approximately 40 GPa. The blood compatibility of the tantalum nitride films, as evaluated by clotting time measurement and platelet adhesion tests, is compared to that of TiN, Ta and low-temperature isotropic pyrolytic carbon (LTIC). Our data reveal that the blood compatibility of our tantalum nitride films is better, and tantalum nitride is thus an excellent material for the fabrication of commercial artificial heart valves.