Objectives : On-Bi-Tang(OB) has been prescribed Chinese traditional medicine for the treatment of inflammatory disease such as chronic renal failure. In this study, we investigated the anti-inflammatory effect of OB extract in the BV2 murine microglial cells. Methods : After the water extract of OB was treated in BV2 cells, murine microglial line, the cell viability was measured by MTT assay. The production of nitric oxide (NO) and $TNF-{alpha}$ was determined based on Griess reagent and enzyme linked immunosorbant assay (ELISA). mRNA expression of inducible nitric oxide synthase (iNOS) and $TNF-{alpha}$ was analyzed by RT-PCR. Results : OB extract significantly inhibited the LPS-induced production of NO and TNF-a in BV2 cells. OB extract also suppressed the mRNA expression of iNOS and $TNF-{alpha}$ in BV2 cells activated with LPS. Conclusion : These data suggests that OB extract may have the anti-inflammatory effect through the modulation of NO production and inflammatory cytokine such as $TNF-{alpha}$.