A bacteriolytic enzyme obtained from the culture fluid of Staphylococcus aureus FDA 209P was purified to homogeneity utilizing dye-ligand affinity column chromatography, hydrophobic interaction high pressure liquid chromatography (HPLC) and hydroxyapatite HPLC. Subsequent characterizations indicated that the purified enzyme acted as endo-beta-N-acetylglucosaminidase. The molecular weight determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) was 51,000 and the isoelectric point was higher than 10. The optimum pH for the enzyme activity on whole cells of Micrococcus luteus as a substrate was 8.0. Some heavy metal cations (Cu2+ and Zn2+) inhibited the enzyme activity at a concentration of 0.1 mM and others (Ba2+, Mg2+ and Co2+) showed a stimulating effect at a concentration of 1 mM.