The catalytic properties of proteases isolated from the filtrate of submerged fermentation of Bacillus subtilis were investigated. Proteases present in the filtrate were determined to be of the serine protease type based on the use of specific protease inhibitors; ethylenediamintetraacetic acid (EDTA) was used as a metalloprotease inhibitor, and phenylmethylsulfonylfluoride (PMSF) was used as a serine protease inhibitor. Protease activity was highly stable in alkaline solutions and at high temperatures as well as in the presence of detergents. We propose that this protease preparation be used as biocomponent in detergent production.