Benzenehexachloride (BHC), as "Gammexane" or "Benexane 50" reduced the hydrolysis of urea by mixed and pure cultures of soil bacteria in solution cultures. It suppressed the development of urea hydrolyzing bacteria in gelatine plate cultures. The reduction or suppression was apparently due to the benzenehexachloride (and not to the "filler" materials in the wettable powder), by interference with the action of the urease, as well as by preventing growth of the bacteria; the gamma isomer had no effect. BHC did not suppress nitrate production from urea in soil.