The electrotransfer of a nucleic acid into tissue cells, in particular in a muscle or a tumoral tissue, is carried out by an electric stimulation of the tissue as follows:first with at least one, preferably a single, pulse of a High Voltage field strength of between 200 and 2000 volts/cmsecond with a single pulse of Low Voltage field strength of between 50 and 200 volts/cm and of duration of between 300 ms and 2000 ms.
