||The purpose of this research was to study the corrosion behavior of Ti-8Ta-3Nb and Ti-10Ta-10Nb in simulated body fluid in comparison to that of CP Ti and Ti-6Al-4V. In the Ringer’s solution, Ti-8Ta-3Nb exhibited a higher passive current density than CP Ti and the other Ti-based alloys. Increasing the alloying additions of Ta and Nb to Ti successfully suppressed the oxygen evolution, lowered the passive current density, and shifted the corrosion potential in the noble direction. While the current densities of CP Ti, Ti-6Al-4V, and Ti-8Ta-3Nb significantly increased at a potential ＞ 1.0 VSSC, the current densities of Ti-10Ta-10Nb tended to remain constant. The XPS spectra showed that the chemical compositions of the passive films formed on Ti-8Ta-3Nb and Ti-10Ta-10Nb consisted of TiO2, Ta2O5, Nb2O5, TaCl5, and NbCl5. The superior property of the passive film on Ti-10Ta-10Nb, in comparison to that on Ti-8Ta-3Nb, was attributed to the presence of the hydrate group inside the passive film.