In this report, the formation of ordered clusters of both spherical and rod-shaped bacteria on an electrode during electrophoretic deposition is described, inside clusters, adhering bacteria are regularly spaced with an interbacterial distance that can be controlled by adjusting the ionic strength of the suspending solution and the DC density used. Formed clusters can be immobilized on the surface by applying a sufficiently high current density. This method enables the design of bacterial biofilms for biotechnological and biomedical applications. When AC fields were used, rod-shaped bacteria adhering on the electrode were seen to align parallel to the applied field. (C) 2000 John Wiley & Sons, Inc.