Genetic approaches are setting the stage for a new understanding of the biological mechanisms underlying blood pressure regulation and hypertension. Recently, substantial progress has been made in elucidating the molecular mechanisms that cause several rare forms of hypertension, including hypertension arising from mutations in the 11 beta-hydroxylase gene, Liddle's syndrome, and glucocorticoid-suppressible aldosteronism. New results have been obtained on the possible role of the angiotensinogen gene, and other candidate genes, such as the angiotensin II receptor Type I gene and the Sa gene, in human hypertension. Investigation of experimental models of hereditary hypertension have also been important in unravelling the genetic complexity of the disease.