The cornea and conjunctiva of the human eye are exposed to external environment and thus are damageable. If the damaged part is infected with some pathogenic microorganisms. serious visual loss may be occured by inflammation. Keratitis or conjunctivitis does not always occur if the eyes are routinely exposed to pathogenic factors because lysozyme in human tears has antimicrobial activity against the microorganisms. 10 this study we have selected 5 strains causing keratitis and/or conjunctivitis. and cultured them in the optimum media. And then we have estimated the growth inhibition of the strains with the addition of various concentration of lysozyme to media to investigate the antimicrobial activity of lysozyme. The results are as follows. The growth of the strains were decreased according to the increase of lysozyme concentration. The growth of Pseudomonas. Neisseria. Klebsiella and Staphylococcus were inhibited 43%, 41%, 35% and 22% respectively by 1 mM concentration of lysozyme. The susceptibility of the gram-negative bacteria to lysozyme is 1.5~2 times higher than the Staphylococcus which is gram-positive bacteria in 1 mM concentration of lysozyme. But lysozyme inhibited the growth of Fusarium which is fungi slightly.