Ti6Al7Nb has been used as an implant material because of its good corrosion resistance and high mechanical properties. However, the presence of aluminium (Al), which may lead to ostemalacia, anaemia and nervous system disorders, limited its wide clinical use. In this study, a titanium oxide (TiO2) nanoporous layer was fabricated on a Ti6Al7Nb alloy using an electrochemical anodic oxidation method. The structure of the TiO2 nanoporous layer was examined by scanning electron microscopy. The chemical compositions of the samples were analysed by X-ray photoelectron spectroscopy (XPS). Biocompatibility was evaluated by culturing rat osteoblast cells. The result showed that TiO2 nanoporous layers comprise a mixed oxide containing TiO2 and a small amount of nobium oxides (Nb2O5) and almost no elemental aluminium. The outer layer of the TiO2 nanoporous layer comprises highly ordered nanotubes and the inner layer forms disordered nanopores. The TiO2 nanoporous layer could support the adhesion, proliferation, differentiation and gene expression of osteoblast cells. Therefore, a TiO2 nanoporous layer could enhance the biocompatibility of Ti6Al7Nb alloy and is as a promising candidate for Ti6Al7Nb alloy implants.