A brief review of the most important properties and fields of application of microbial proteinases are presented. Special possibilities of an industrial utilization of these enzymes are discussed: in the photographic industry for the production and degradation of gelatin as well as for silverless photography, in the food industry for the improvement of the functional properties of proteins as well as for increasing their nutritive value, in organic synthesis for the production of peptides, and in sewage treatment plants for the stabilization of sludge.