Hydroxyapatite/titania bio-nano-composites with different ratios have been successfully synthesized by combined high gravity and hydrothermal approaches. Initial colloidal nanoparticles were prepared by high gravity method and then the nanoparticles were treated hydrothermally. Detailed characterization was carried out by using XRD, FESEM and TEM analysis. Bioactive nature of the nanocomposites was analyzed by using osteoblast-like Chinese hamster ovary cells (CHO-K1, Korean Collection for Type Cultures). HAp/TiO 2 nanocomposites showed good bioactivity for higher HAp content. Antimicrobial property of the bio-nano-composite was carried out by well-diffusion method against pathogenic organisms such as Escherichia coli (E. coli-Gram negative) and Staphylococcus aureus (S. aureus-Gram positive). The antimicrobial property increased upon the increase of the TiO 2 concentration, but at a particular composition the property was better than the pure TiO 2. Also the antimicrobial property was more pronounced with the positive bacteria than the negative one. The results showed that the bioactivity and antimicrobial property changed inversely depending upon the HAp/TiO 2composite ratio. © 2012 Elsevier B.V.