Deposition of four bacterial strains from a 1 mM potassium phosphate buffer (pH 7) to an indium tin oxide (ITO) electrode surface has been studied in a parallel plate flow chamber at three electrode potentials (-0.2, 0.1, and 0.5 V). Capacitance measurements demonstrated that the ITO surface was negatively charged with respect to the solution at the electric potentials applied, that is, bacteria deposited under repulsive electrostatic conditions. Initial deposition rates were independent of the electrode potential, except for Actinomyces naeslundii T14V-J1. Application of a more negative electrode potential yielded increased desorption of Streptococcus oralis J22, Staphylococcus epidermidis 3399, and A. naeslundii 147, whereas for A. naeslundii T14V-J1 desorption decreased. If a high (greater than or equal to 65 muA) cathodic current was applied by adjusting the potential between -0.4 and -0.5 V, adhering bacteria were stimulated to desorb with desorption probabilities increasing with increasing current density. Bacterial desorption could be described on the basis of the Derjaguin-Landau-Verwey-Overbeek theory assuming secondary minimum adhesion, except for A. naeslundii T14V-J1. When bacteria were forced to adhere in the primary minimum by application of a high (1.8 V) positive electrode potential during deposition, adhering bacteria could hardly be stimulated to desorb, indicating strong, irreversible adhesion. The deviating behavior of A. naeslundii T14V-J1 was attributed to direct contact between its relatively long surface appendages and the electrode surface.