The dielectric measurement of Escherichia coli suspension was carried out between 0.01 and 100 MHz during cell disruption using a physical method or fell lysis induced by chemicals for the purpose of on-line monitoring of cell disruption or lysis of bacterial cells. The dielectric dispersion of relative permittivity centered at about 1.4 MHz and the dielectric parameters based on the fitting calculation well reflected the damage of these cells under physical and chemical stresses. The degree of cell disruption as determined by the dielectric parameters, the amplitude of dispersion and the conductivity, wed corresponded to those obtained by other conventional kinetic analyses. This methodology can be utilized for the on-line monitoring of physical cell disruption and cell lysis induced by detergent and could provide direct information to control these processes. Based on these results, the dielectric measurement was successfully applied to monitor the stress-mediated cultivation of E. coli cells.