The carbonate-containing barium hydroxyapatite was prepared by solid state reactions in air at 950°C. Obtained samples were investigated by X-ray powder diffraction and IR spectroscopy. The stoichiometry of these samples conforms to Ba5(PO4)3-x(CO3)x(OH)1-xOx as the result of CO3 2 and O2- substitution for PO4 3 and OH- in the hydroxyapatite lattice under the scheme: PO4 3 + OH- _ CO3 2 + O2-. The crystal structure of some carbonated barium hydroxyapatite patterns were refined by Rietveld method using X-ray powder diffraction data. The analysis of the crystallographic site occupation has shown that the single phase range of Ba5(PO4)3-x(CO3)x(OH)1-xOx is limited by x = 0.32.