Abstract Calcium silicate–poly(n-butyl-2-cyanoacrylate) nanocomposite has been studied as a promising biomaterial to immobilize small bone fragments in order to achieve adequate fracture healing. The aim of this work was to investigate the in-vitro and in-vivo biocompatibility of the synthetic nanocomposite produced. The samples were characterized by means of infrared spectroscopy, thermogravimetric analysis, scanning and transmission electron microscopy. Bioactivity, degradability, cytotoxicity and implantation tests were performed. Experimental results showed the degradability of the nanocomposite, no cytotoxicity and a significant apatite nucleation and growth on the material surfaces after seven days of immersion in simulated body fluid. The new bone formation observed on the surface of the nanocomposite implanted in vivo is an indicator of its biocompatibility.