Multistage character of adsorption isotherms of human and bovine serum albumins on hydroxyapatite nanoparticles from aqueous solution have been developed by the radionuclide-microscopy method. Such a character of isotherms indicated the number of physicalchemical processes: formation of the peptide-nanohydroxyapatite complex and following by aggregation in liquid and solid phases. This hypothesis was confirmed by X-ray and dynamic light-scattering analysis, It was shown, that when hydroxyapatite is formed in albumin solution the peptide-nanohydroxyapatite complex formation is followed by morphology and structure exchange of hydroxyapatite nanocrystals.