This study concerned the production, purification and application of extracellular chitinase from Cellulosimicrobium cellulans strain 191. In shaken flasks the maximum yield of chitinase was 6.9 U/mL after 72 h of cultivation at 25°C and 200 rpm. In a 5 L fermenter with 1.5 vvm aeration, the highest yield obtained was 4.19 U/mL after 168 h of fermentation at 25°C and 200 rpm, and using 3 vvm, it was 4.38 U/mL after 144 h of fermentation. The chitinase (61 KDa) was purified about 6.65 times by Sepharose CL 4B 200 gel filtration with a yield of 46.61%. The purified enzyme was able to lyse the cell walls of some fungi and to form protoplasts.40623-30