Micro- and nano-patterning/modification are emerging strategies to improve surfaces properties that may influence critically cells adherence and differentiation. Aim of this work was to study the in vitro biological reactivity of human bone marrow mesenchymal stem cells (hBMSCs) to a nanostructured titanium dioxide (TiO₂) surface in comparison to a coverglass (Glass) in two different culture conditions: with (osteogenic medium (OM)) and without (proliferative medium (PM)) osteogenic factors. To evaluate cell adhesion, hBMSCs phosphorylated focal adhesion kinase (pFAK) foci were analyzed by confocal laser scanning microscopy (CLSM) at 24 h: the TiO₂ surface showed a higher number of pFAK foci with respect to Glass. The hBMSCs differentiation to osteoblasts was evaluated in both PM and OM culture conditions by enzyme-linked immunosorbent assay (ELISA), CLSM and real-time quantitative reverse transcription PCR (qRT-PCR) at 28 days. In comparison with Glass, TiO₂ surface in combination with OM conditions increased the content of extracellular bone proteins, calcium deposition and alkaline phosphatase activity. The qRT-PCR analysis revealed, both in PM and OM, that TiO₂ surface increased at seven and 28 days the expression of osteogenic genes. All together, these results demonstrate the capability of TiO₂ nanostructured surface to promote hBMSCs osteoblast differentiation and its potentiality in biomedical applications.