In Bacillus subtilis grown under aeration at 37° for 24 h in liquid nutrient medium containing the nonionic detergents octylphenol-polyethylene glycol ether or polyoxyethylene monocetyl ether, increasing the concentrations of the detergents led to a decrease in the amount of protease secreted from the cells and abolished sporulation. Possible mechanisms by which these detergents caused these actions are discussed.