Objectives : In this study, the effects of ethylacetate extract of Ostericum koreanum on inflammation in RAW264.7 cells were investigated. Methods : Dried roots of Ostericum koreanum was extracted with 80% methanol for 24 h, and then fractionated with n-butanol, n-hexan and ethylacetate. RAW264.7 cells, a mouse macrophage line were incubated with different concentrations of the extract for 30 min and then stimulated with LPS at indicated times. Cell toxicity was determined by MTT assay. The concentrations of nitric oxide (NO) and prostaglandin E2 ($PGE_2$) were measured by Griess assay and enzyme immunoassay (EIA), respectively. The expressions of inducible nitric oxide synthease (iNOS) and cyclooxyganase (COX) -2 mRNA and protein were determined by RT-PCR and Western blot. Results : The methanol extract of Ostericum koreanuman and its fractions were significantly inhibited the NO and PGE2 productions in LPS-stimulated RAW264.7 cells. Among the fractions of Ostericum koreanuman the ethylacetate fraction was more strongly inhibited NO and $PGE_2$ productions compared with other fractions. The ethylacetate fraction was also suppressed LPS-induced mRNA expressions of iNOS and its protein levels in RAW264.7 cells. Conclusions : This study suggests that the ethylacetate fraction of Ostericum koreanum may have an anti-inflammatory property through suppressing inflammatory mediator productions in activated macrophages, suggesting have a therapeutic potential for the treatment of various inflammatory diseases.