Biomimetic carbonated fluorapatite-gelatine composite were grown by a double-diffusion technique within a gelatine gel. In the biomimetic carbonated fluorapatite the carbonate ions replace the phosphate groups (so-called B-type substitution). The carbonate content in the synthetic fluorapatites varies from 0,05 to 7,5 wt.-%. Besides the "built-in" carbonate ion in the fluorapatite crystal structure we also determined sodium and hydrophoshate ions, water molecules and trace amounts of hydroxy! ions. The amount of vacancies on the calcium site as well as within the channels of the apatite crystal structure increases with the increase of carbonate content. The chemical composition and lattice parameters of the biomimetic carbonated fluorapatites are similar to those of apatite of hard tissues of some living and fossil organisms, but significantly different from apatite of sedimentary phosphorites.