Fluorine and chlorine co-substituted hydroxyapatites (HAP) were prepared through aqueous precipitation method. Characterization results from X-ray diffraction (XRD) revealed that co-substitution of these anions resulted in the formation of pure HAP phase except for the small observed difference in the lattice parameters of the resultant apatites. The elemental analysis and FT-IR results have also confirmed the incorporation of substituted anions in the apatite structure. The calculated crystallite size for all anionic substituted apatite fall well below the range of 50 nm size that tend to coincide with the value of bone mineral crystallite size.