The use of electric pulses to transfect cells has recently been extended to show the utility of this procedure in vivo. Electrotransfer has been performed in vivo on several tissue types including skin, blood vessels, liver, tumor, muscle, cornea, brain and spleen. The most widely targeted tissue has been skeletal muscle. In addition to its potential use in gene therapy, in vivo DNA electrotransfer is also, because of its simplicity, a powerful laboratory tool to study in vivo gene expression and function in a given tissue. Many published studies have now shown that plasmid electrotransfer can lead to a long-lasting therapeutic effect in various pathologies, such as cancer, blood disease, or muscle ischemia. The future potential for this gene therapy approach will include delivery for both local action or distal effect by secretion of the transgenic proteins in the circulation.