The beta-glucosidase of aHumicola sp. is partly characterized. The pH and temperature optima, thermal stability and Michaelis constants with p-nitrophenyl-beta-D-glucoside (PNPG) substrate suggest the existance of at least one extracellular and one intracellular enzyme. The extracellular activity is substantially more than that produced byTrichoderma reesei QM 9414.