The dependence of cytotoxicity on particle size in ceramic materials was investigated by biochemical functional analysis, in vitro using cells as probes and in vivo in animal implantation. The nanoparticles and carbon nano-tubes have the phlogogenic property according to their size. The nanoparticles were phagocytized by cells. The in vitro showed the cytotoxicity due to particle size effect. The results show that the cytotoxicity was induced due to the physical size effect in the range less than 100μm.