In the paper the structure of lysozyme (muramidase) and factors affecting lysozyme activity (temperature, chemicals and complexes) were reviewed. Lysozyme has been found to be heat stable in acidic solutions, but to be inactivated quickly in alkaline conditions. Sugar, salt, polyols, some amino acids and spices stabilized lysozyme. Enzyme complexes with egg yolk and some eeg-white components and polyvalent cations inactivated lysozyme.