The cardinal role of the intrarenal renin-angiotensin system (RAS) in the control of sodium excretion and the pathophysiology of hypertension continues to receive increased attention. In addition to its very powerful vasoconstrictor action, angiotensin (Ang) II exerts important actions on tubular transport function and several recent studies have emphasized the potential importance of actions of angiotensin peptides on receptors localized to the luminal membranes of both proximal and distal nephron segments. Furthermore, a strong case is being developed supporting the importance of local mechanisms regulating the activity of the RAS. This is due to the fact that all components of the RAS are strongly expressed in the kidneys.