We review the available methods of creating genetically engineered kidneys. These include transgenic technology to introduce novel genes or delete existing genes and methods of gene transfer into the post-natal or adult kidney. The use of such technology has provided insights into renal development and growth and created new animal models of human diseases. Although some of these techniques are of potential use for introducing therapeutically useful gene products into the diseased kidney, many problems remain to be solved before this aim is attained.