Activation of the renin-angiotensin (Ang) system induces inflammation via interaction between Ang II and type 1 receptor on leukocytes. The relevance of the new arm of the renin-Ang system, namely Ang-converting enzyme-2/Ang-(1-7)/Mas receptor, for inflammatory responses is not known and was investigated in this study. For this purpose, two experimental models were used: Ag-induced arthritis (AIA) in mice and adjuvant-induced arthritis (AdIA) in rats. Male C57BL/6 wild-type or Mas(-/-) mice were subjected to AIA and treated with Ang-(1-7), the Mas agonist AVE 0991, or vehicle. AdIA was performed in female rats that were given AVE 0991 or vehicle. In wild-type mice, Mas protein is expressed in arthritic joints. Administration of AVE 0991 or Ang-(1-7) decreased AIA-induced neutrophil accumulation, hypernociception, and production of TNF-α, IL-1β, and CXCL1. Histopathological analysis showed significant reduction of inflammation. Mechanistically, AVE 0991 reduced leukocyte rolling and adhesion, even when given after Ag challenge. Mas(-/-) mice subjected to AIA developed slightly more pronounced inflammation, as observed by greater neutrophil accumulation and cytokine release. Administration of AVE 0991 was without effect in Mas(-/-) mice subjected to AIA. In rats, administration of AVE 0991 decreased edema, neutrophil accumulation, histopathological score, and production of IL-1β and CXCL1 induced by AdIA. Therefore, activation of Mas receptors decreases neutrophil influx and cytokine production and causes significant amelioration of arthritis in experimental models of arthritis in rats and mice. This approach might represent a novel therapeutic opportunity for arthritis.