Endopleura uchi (Huber) Cuatrec. (Humiriaceae), the Brazilian Amazon plant, is used in folk medicine to treat arthritis and gastric ulcer. Bergenin, one of the chemical constituents of E. uchi, has antiinflammatory properties. Its acetylation results in acetylbergenin, which is extracted to investigate its potential anti-inflammatory and antiulcer properties using an assay for croton oil-induced ear edema, rat paw edema induced by carrageenan and dextran, carragenin-induced peritonitis, and stress-induced gastric ulcer. In ear erythema induced by croton oil, acetylbergenin presented a significant 75.60% inhibition (p<0.001). The oral administration of 6.8 mg/kg of acetylbergenin significantly inhibited the carrageenan-induced edema formation by 35.09% (p<0.05) and the dextran-induced edema by 33% (p<0.05). The migration of neutrophils toward the peritoneal cavity was inhibited in acetylbergenin (6.8 mg/kg) treated animals by 70% (p<0.01). In the stress-induced gastric ulcer, acetylbergenin inhibited 78.55% of gastric lesions. The results suggest that, the anti-inflammatory action of acetylbergenin appears to be dependent on cyclooxygenase (COX-2) inhibition. Furthermore, although the antiinflammatory activity of acetylbergenin is a characteristic of nonsteroidal compounds, it causes little deleterious interference in the gastric mucosa.