This research was undertaken to find the in vitro inflammatory action of the essenetial oil (CS-oil) extracted from Chrysanthemum sibiricum (Compositae) herbs. We investigated the effects of the CS-oil not only on the formation NO, $PGE_2$, and $TNF-{alpha}$ but also on inducible nitric oxide synthase and cyclooxygenase-2 (COX-2) in lipopolysaccharide (LPS)-induced murine macrophage RAW 264.7 cells. The data obtained were consistent with the modulation of iNOS enzyme expression. A similar fashion was also observed when LPS-induced $PGE_2$ release and COX-2 expression were tested. The significant inhibitory effects were shown in concentration-dependent manners. In addition, CS-oil also mildly but significantly reduced the formation of TNF-a. These findings support the application of CS-oil as an antiinflammatory essential oil.