A recently developed novel Ti-29Nb-13Ta-4.6Zr alloy (Ti-Ta) was investigated physically and chemically, and the results suggested it to be a possibly suitable dental material. In this study we analyzed the effects of the alloy, in comparison with those of other dental metals, on the adhesion, spreading, and proliferation of human gingival fibroblasts (Gin-1 cells) in vitro. The Gin-1 cells adhered and spread well on the Ti-Ta as well as on commercially pure titanium (Ti) and commercial Ti-6Al-7Nb alloy (Ti-Al), forming long processes showing a typical fibroblastic morphology that was close to that on glass. The proliferation of Gin-1 cells was significantly suppressed on Au-Pd-Ag alloy (Au-Pd) and commercially pure copper (Cu); however, the cells proliferated as well on Ti-Ta as they did on Ti, Ti-Al, and glass. Though most of the Gin-1 cells on Cu and about half of them on Au-Pd died after 1 day and 5 days of culture, respectively, the cells on Ti-Ta, Ti, Ti-Al and glass showed 100% viability even after 5 days of culture. These results suggest that the newly developed Ti-Ta alloy has biocompatibility as good as that of Ti and Ti-Al with respect to morphology and proliferation of Gin-1 cells in vitro.