The possibility of continuously on-line measuring the growth of Salmonella typhimurium on solid medium was studied The medium used is SS agar which is not only suitable for isolation and identification of Gram-negative intestinal bacilli but also fit for monitoring bacteria with a thickness shear mode (TSM) acoustic resonator in series. It was found that the method is simple, realtime, and rapid The concentration of the bacteria detected by this method was in the range of 10(2)-3.6 x 10(6) cells ml(-1).