Experimental hypertension research has advanced primarily through pharmacologic and physiologic experiments, as well as classic breeding studies in whole animal models. Information obtained from these interventions has recently been enhanced by the identification of candidate genes, which could be contributing to the pathophysiology of hypertension. Transgenic techniques have a significant impact in this context by linking the information derived from the genetic studies to the hypertensive phenotype. Most commonly, transgenic experiments are carried out to add specific gene sequences, and this is routinely performed by direct microinjection of DNA consisting of regulatory and coding sequences into the pronucleus of fertilized oocytes. Homologous or heterologous regulatory sequences are responsible for targeting the expression of genes to tissues and cells. The effect of this gene addition on the phenotype can then be analyzed by using the methodologic arsenal of cardiovascular physiology and pharmacology. The majority of transgenic studies have been carried out in mice, but recent efforts have also focused on other species, such as the rat. In addition, new techniques are available, which include the use of homologous recombination in embryonic stem cells to perform gene-deletion studies or the application of cell-specific promoters to target and knockout gene expression in specific tissues.