The process of multilayer assembly via layer-by-layer deposition of linear polyions anti lysozyme have been studied. The films were fabricated on glass slides by alternate electrostatic adsorption of anionic poly(styrenesulfonate) (PSS), cationic poly(allylamine) (PAA) polyions and hen egg-white lysozyme. The multilayer build-up was monitored by the small-angle X-ray diffraction method. X-ray reflectivity curves from the films measured at different steps of the assembly reveal Kiessig fringes. From their periodicity the film thickness was calculated. The growth step for a PSS/PAA bilayer equals 37 Angstrom. The thickness of the lysozyme layer equals 45 Angstrom, which is close to dimensions of the lysozyme molecule determined by X-ray crystallography. An analysis of surface charges of the lysozyme molecule shows some preferentially positive charged regions, which are the most probable sites of interactions with negatively charged PSS.