A method for the laboratory-scale production and isolation of chitosan (polyglucosamine) by liquid and solid-state fermentation from Lentinus edodes was developed. The yields of isolated chitosan were 120 mg/L of fermentation medium under liquid fermentation conditions and 6.18 g/kg of fermentation medium under solid-state fermentation conditions. The latter method, which gives up to 50 times yields than other chitosan production methods from fungi, provides a new flexible and easily scaled-up procedure for the production of low acetylation degree chitosan.