Abstract In this study, the chitinolytic activity of rhizosphere bacteria was detected on a 0.2% colloidal chitin agar medium. A zone of clearance indicating chitinase activity was observed around the discs in Paenarthrobacter nicotinovorans, Chitinophaga oryziterrae, and Bacillus stratosphericus. For the determination of the pH stability of the bacterial chitinase, the three bacterial isolates were incubated at different pH ranges from pH 3~7. All three isolates showed the highest chitinase activity at pH 4. Five chitinase isozymes (66, 57, 49, 45 and 36 kDa) and one chitosanase (40 kDa) were detected in P. nicotinovorans. While C. oryziterrae did not. P. nicotinovorans showed the highest antifungal activity on PDA against Botrytis cinerea and Colletotirchum higginisianum. However, in the potato dextrose broth, C. oryziterrae showed the highest antifungal activity based on the fungal mycelial dry weight measurement. These results indicate that three chitinase-producing rhizosphere bacteria can potentially be used as biocontrol agents in agricultural applications.