A simple hydrothermal procedure was implemented to prepare hydroxyapatite (HAp) nanorods grown on graphene oxides (GO) sheet. The crystalline structure, chemical composition and morphology of the as-prepared nanocomposites were characterized by using X-ray diffraction, Raman spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). Nanorods like HAp nanostructure with the diameter and length in the range of similar to 32 and 60-85 nm were uniformly grown on GO sheets. A possible formation mechanism of HAp nanorods grown on GO is proposed. Further, the bio-physical properties of HAp/GO nano composites were studied by using Bovine Serum Albumin (BSA) as a model protein. The particle surface effects on the BSA structure, the HAp/GO -protein composites were studied by circular dichroism (CD) between 200 and 260 nm. Result conforms, the primary structure of the 10 mu M BSA exhibits a characteristic alpha-helix spectrum between wavelength 200-240, after 12 h incubation of the BSA with HAp/GO, no significant change in the alpha helix pattern of the BSA. Moreover, human skin cancer cells (A431) was used to determine the cytotoxicity of HAp/GO nanocomposites at various concentrations of 50-500 mu g/mL for 24 h and the cytotoxicity was observed using MTT assays. The as-prepared HAp/GO nanocomposites showed no cytotoxicity effects on A431 cancer cell lines. Significance of this study shows that the as-prepared HAp/GO nanocomposites provide excellent biocompatibility which was used orthopedic, drug delivery and dentistry applications. (C) 2017 Elsevier B.V. All rights reserved.