BACKGROUND/OBJECTIVES: Overproduction of nitric oxide (NO) by the inducible nitric oxide synthase (iNOS) enzyme can cause inflammation. Cyclooxygenase-2 (COX-2) is also involved in the inflammatory response through regulation of nuclear factor-kappa B $NF-{kappa}B$(). Areca catechu is one of the known fruit plants of the Palmaceae family. It has been used for a long time as a source of herbal medicine in Indonesia. In this study, we explored the effect of Indonesian Areca catechu leaf ethanol extract (ACE) in lipopolysaccharide (LPS)-induced inflammation and carrageenan-induced paw edema models. Recently, this natural extract has been in the spotlight because of its efficacy and limited or no toxic side effects. However, the mechanism underlying its anti-inflammatory effect remains to be elucidated. MATERIALS/METHODS: We measured NO production by using the Griess reagent, and determined the expression levels of inflammation-related proteins, such as iNOS, COX2, and $NF-{kappa}B$, by western blot. To confirm the effect of ACE in vivo, we used the carrageenan-induced paw edema model. RESULTS: Compared to untreated cells, LPS-stimulated RAW 264.7 cells treated with ACE showed reduced NO generation and reduced iNOS and COX-2 expression. We found that the acute inflammatory response was significantly reduced by ACE in the carrageenan-induced paw edema model. CONCLUSION: Taken together, these results suggest that ACE can inhibit inflammation and modulate NO generation via downregulation of iNOS levels and $NF-{kappa}B$ signaling in vitro and in vivo. ACE may have a potential medical benefit as an anti-inflammation agent.