Nano-sized carbonated hydroxyapatite (CHAp) particles were firstly synthesized using a nanoemulsion method. TEM analyses revealed that as-synthesized nanoparticles were calcium-deficient and spherical in shape (diameter: 16.8±2.6nm). Biocomposite microspheres comprising CHAp nanoparticles and poly(L-lactide) (PLLA) were fabricated using the single emulsion solvent evaporation technique. SEM images showed that composite microspheres were mainly 5-30 μm in size despite the change of CHAp nanoparticle content. When the CHAp nanoparticle content in composite microspheres was below 10 wt%, all nanoparticles were encapsulated within the microspheres which possessed a nanocomposite structure. DSC results showed that the crystallinity of the PLLA matrix of microspheres increased from 38 to 42% when the CHAp nanoparticle content was increased from 0 to 20 wt%. The biocomposite microspheres should be a suitable material for constructing bone tissue engineering scaffolds.