Absidia orchidis can be used as a source of several enzymes, amongst which chitosanase is one of the most interesting. Chitosanase hydrolyses the links between the mers of glucosamine or between mers of glucosamine and N-acetylglucosamine in the chains of chitosan and chitin. The aim of the presented work was the preliminary investigations of the chitosanase from the fungus Absidia orchidis. This chitosanase is an intracellular enzyme with molecular weight approx. 36 000 Da. The optimal conditions for a hydrolysis of chitosan were pH 4.5 and temperature 25C. This enzyme is stable at the optimal temperature for 24-48 hours, but after 7 days it was inactivated.