In the present study, the effects of several triterpenes isolated from the leaves of Acanthopanax chiisanensis (Araliaceae), namely, chiisanoside, isochiisanoside, 22-hydroxychiisanoside and chiisanogenin (the aglycone of chiisanoside) were evaluated on lipopolysaccharide (LPS)-induced nitric oxide (NO) and prostaglandin E₂ (PGE₂) production by the RAW 264.7 macrophage cell line. Of the triterpenes tested, chiisanoside was found to most potently inhibit NO and PGE₂ production. In addition, chiisanoside significantly reduced the release of inflammatory cytokines like TNF-α and IL-1β. Consistent with these observations, the protein and mRNA expression levels of iNOS and COX-2 enzyme were found to be inhibited by chiisanoside in a concentration-dependent manner. Furthermore, chiisanoside inhibited the nuclear factor-κB (NF-κB) activation induced by LPS and this was associated with a reduction in p65 protein in the nucleus and with the phosphorylations of ERK1/2 and JNK MAP kinases. Taken together, our data indicate that the anti-inflammatory properties of chiisanoside might be the result from the inhibition of iNOS, COX-2, TNF-α and IL-1β expression through the down-regulation of NF-κB binding activity.