Many experimental data have suggested that the renin-angiotensin system participates in immune and inflammatory responses. Angiotensin II is involved in several steps of the inflammatory process: mononuclear cells respond to angiotensin II stimulation (cell proliferation and chemotaxis); angiotensin II regulates the recruitment of proinflammatory cells into the site of injury (mediated by the expression of vascular permeability factors, adhesion molecules and chemokines by resident cells); inflammatory cells can produce angiotensin II, and might therefore contribute to the perpetuation of tissue damage. In this review, we summarize the proinflammatory properties of angiotensin II, to demonstrate the novel role of this vasoactive peptide as a true cytokine. We will show the information obtained as a result of the pharmacological blockade of the renin angiotensin system, which has demonstrated that this system is involved in immune and inflammatory diseases. In this aspect, we discuss the molecular mechanism of angiotensin II-induced tissue damage, as well as its contribution to the pathogenesis of several diseases, including atherosclerosis, hypertension and renal damage, showing that angiotensin II plays an active role in the inflammatory response of these diseases.