The octapeptide angiotensin II (AngII) plays a homeostatic role in the regulation of blood pressure and water and electrolyte balance, and contributes to the progression of cardiovascular remodeling. AngII activates AngII type 1 (AT1) receptor and type 2 (AT2) receptor, both of which belong to the seven-transmembrane, G protein-coupled receptor family. Most of the actions of AngII such as promotion of cellular proliferation, hypertrophy, and fibrosis are mediated by AT1 receptor. However, in some pathological situations, AT2 receptor showed an increase in expression level and functions to antagonize the actions by AT1 receptor stimulation. Recent studies have advanced our understanding of the molecular mechanisms underlying receptor activation and signal transduction, and elucidated the pathophysiological roles of AT1 and AT2 receptors in the cardiovascular system.