Electrooptical and conductometric methods continue to reveal new and more detailed information on the dynamic properties of membranes in electric fields. In particular, the electric pore formation in lipid vesicles, doped with optical probes, has been successfully investigated with electrooptical techniques thus providing new insight into the lipid rearrangements underlying membrane electroporation (ME) and vesicle deformation. Progress in understanding the molecular mechanism of ME and related phenomena, such as electrofusion of cells or electroinsertion of foreign proteins into membranes, is crucially important for the numerous applications of ME, for example, direct electroporative gene transfer and drug delivery in the new medical discipline of electroporative chemotherapy.