Electroporation involves the application of high-voltage, short-duration electric pulses to transiently disrupt lipid barriers in the body. For vaccination, electroporation has been used to increase stratum corneum permeability and thereby enable vaccine entry into the skin. Electroporation has also been used to permeabilize cells within the skin and thereby drive, for example, DNA vaccines into epidermal and dermal cells (Fig. 4b) . Electroporation has been well established as a tool for delivering molecules across the stratum corneum (Prausnitz et al. 1993) or across the cell membranes (Bilitewski et al. 2003) . Many studies have focused on the use of electroporation for DNA vaccination. This is not surprising given the long history of use of electroporation for delivery of DNA into cells in vitro. However, many electroporation studies involve insertion of electrode needles into the skin. Some studies have demonstrated the use of electroporation for topical vaccine delivery (Zhao et al. 2006) . In one study, electroporation has been found to stimulate the exodus of Langerhans cells from the skin, which is likely to have an adjuvant-like effect (Zhao et al. 2006) . In this study, the efficacy of peptide delivery was found to be comparable to that of ID injected with Freund's complete adjuvant. Further, the peptide-specific CTL response to the vaccine delivered by electroporation was equivalent to that delivered by ID injection.