One hundred and fourteen bacterial cultures representing most of the species in theBacillusgenus were tested for the production of extracellular barley gum cytase. Assays were made on shake-flask cultures grown on a medium containing glucose and yeast extract. Although all the organisms had some enzymatic activity, certain strains ofBacillus subtilisgave the best yields of cytase. On a medium with asparagine as the sole nitrogen source even higher yields were obtained. The crude cytase preparations were stable and after freeze-drying most of the original activity remained.