Angiotensin II is an octapeptide hormone of the renin-angiotensin system (RAS), and it regulates a wide variety ofphysiological responses including salt and water balance, the blood pressure and the vascular tone. Clinical trialswith angiotensin-converting enzyme (ACE) inhibitors have demonstrated survival benefits in subjects with congestiveheart failure and myocardial infarction, and this support the importance of angiotensin II in the pathogenesisof cardiovascular diseases. Through activation of small G proteins such as Ras, Rho, and Rac, angiotensin II inducesremodeling of vascular smooth muscle cells (VSMC), including proliferation, migration, hypertrophy and inflammation.Angiotensin (1-7) appears to be the main effector peptide of ACE2 with vasodilatory, natriuretic andantiinflammatory properties. The cross-talk between the angiotensin II receptors may play an important role inmaintaining cardiovascular homeostasis. (Korean Circulation J 2007;37:91-96)