Galla Rhois is a nest of parasitic bug, has been traditionally used for the treatment of the therapy of diarrhea, peptic ulcer, hemauria, etc., that showed various anti-inflammatory activity, and other biological properties. We studied the effect of Galla Rhois ethanol extract. we investigated whether compounds isolated from the ethanol extract of Galla Rhois, could modulate iNOS and COX-2 expression in RAW 264.7 macrophages stimulated with lipopolysaccharide (LPS). We found compounds that suppressed LPS-induced iNOS and COX-2 expression. Suppression of the expression of iNOS and COX-2 was in parallel with the comparable inhibition of the production of nitric oxide (NO) and prostaglandin E2 (PGE2). Our results suggest that compounds can inhibit NO and PGE2 productions through suppression of LPS-induced iNOS and COX-2 expression. Because COX-2- or iNOS-dependent mechanisms are involved in inflammation and tumor progression, our findings provide a new uncovering mechanism responsible for anti-inflammatory and antitumor effects of Galla Rhois.