Echinodorus macrophyllus leaf has been used in Brazilian folk medicine to treat inflammatory conditions and kidney dysfunctions. The present study evaluated the effects of leaf ethanolic extract from E. macrophyllus (EEEm) in acute and subchronic models of inflammation. The EEEm was found to cause significant and potent inhibition of carrageenan- and dextran-induced paw edema in rats and marked decreases in the exudate volume and leukocyte migration in rats with carrageenan-induced pleurisy, the vascular permeability increase induced by intraperitoneal acetic acid, and the croton oil-induced topical ear edema in mice. On the other hand, the EEEm was not active in the test model of cotton pellet-induced granuloma in rats. Phytochemical analysis with E. macrophyllus leaves revealed the presence of triterpenoids, steroids, flavones, flavonols, and xanthones. Two flavonoids were isolated from the ethyl acetate fraction and identified as isovitexin and vitexin. Our results support the traditional use of E. macrophyllus leaves in the treatment of acute inflammatory conditions.