The techniques of electroporation and electrofusion require that cells be subjected to brief pulses of electric fields of the appropriate amplitude, duration, and wave form. In this chapter, the term electro cell manipulation (ECM) shall describe both techniques. ECM is a quite universal technique that can be applied to eggs, sperm, platelets, mammalian cells, plant protoplasts, plant pollen, liposomes, bacteria, fungi, and yeast—generally to any vesicle surrounded by a membrane. The term “cells” will be used representatively for any of the vesicles to be manipulated unless specific requirements dictate otherwise.