We developed a new in vivo electroporation method to deliver genes into retinal ganglion cells (RGCs). Efficiency and degree of tissue damage were evaluated using green fluorescent protein (GFP) gene and TUNEL. Soon after the intravitreous injection of the GFP gene, electroporation (five electric pulses of 99 ms duration each and 12V/cm delivered twice 5 min apart) was carried out on the adult rat eyeball with the aid of tweezer-type disc electrodes attached to corneal (cathode) and scleral (anode) surfaces. GFP expression, exhibiting a maximum on day 7, was detectable for up to 21 days. DiI retrograde labeling of RGCs showed that 41.5% of the total ganglion cells in the electroinjected area were GFP-positive. Therefore, this new method may be a useful tool for the delivery of genes into RGCs.