Aerial parts of Artemisia asiatica (Compositae) have been traditionally used as an oriental medicine for the treatment of inflammatory and ulcerogenic diseases. In the present study, artemisolide was isolated as a nuclear factor $(NF)-{kappa}B$ inhibitor from A. asiatica by activity-guided fractionation. Artemisolide inhibited $NF-{kappa}B$ transcriptional activity in lipopolysaccharide (LPS)-stimulated macrophages RAW 264.7 with an $IC_{50}$ value of $5.8;{mu}M$. The compound was also effective in blocking $NF-{kappa}B$ transcriptional activities elicited by the expression vector encoding the $NF-{kappa}B$ p65 or p50 subunits bypassing the inhibitory kB degradation signaling $NF-{kappa}B$ activation. The macrophages markedly increased their $PGE_2$ and NO production upon exposure to LPS alone. Artemisolide inhibited LPS-induced $PGE_2$ and NO production with $IC_{50}$ values of $8.7;{mu}M$ and $6.4;{mu}M$, respectively, but also suppressed LPS-induced synthesis of cyclooxygenase (COX)-2 or inducible NO synthase (iNOS). Taken together, artemisolide is a $NF-{kappa}B$ inhibitor that attenuates LPS-induced production of $PGE_2$ or NO via down-regulation of COX-2 or iNOS expression in macrophages RAW 264.7. Therefore, artemisolide could represent and provide the anti-inflammatory principle associated with the traditional medicine, A. asiatica.