Renal gene therapy may offer new strategies to treat diseases of native and transplanted kidneys. Several experimental techniques have been developed and employed using nonviral, viral, and cellular vectors. The most efficient vector for in vivo transfection appears to be adenovirus. Glomeruli, blood vessels, interstitial cells, and pyelum can be transfected with high efficiency. In addition, electroporation and microbubbles with ultrasound, both being enhanced naked plasmid techniques, offer good opportunities. Trapping of mesangial cells into the glomeruli as well as natural targeting of monocytes or macrophages to inflamed kidneys are elegant methods for site-specific delivery of genes. For gene therapy in kidney transplantation, hemagglutinating virus of Japan liposomes are efficient vectors for tubular transfection, whereas enhanced naked plasmid techniques are suitable for glomerular transfection. However, adenovirus offers the best opportunities in a renal transplantation setup because varying parameters of graft perfusion allows targeting of different cell types. In renal grafts, lymphocytes can be used for selective targeting to sites of inflammation. In conclusion, for both in vivo and ex vivo renal transfection, enhanced naked plasmids and adenovirus offer the best perspectives for effective clinical application. Moreover, the development of safer, nonimmunogenic vectors and the large-scale production could make clinical renal gene therapy a realistic possibility for the near future.