Objectives : Coptidis Rhizoma has been known traditional medicine with antimicrobial activities. We investigated inhibitory effects of Coptidis Rhizoma extract on lipopolysaccharide(LPS)-induced nitric oxide production from mouse macrophages. Methods : After Coptidis Rhizoma extract was pretreated in BV2, mouse brain macrophages and RAW264.7 mouse macrophages, cells were activated with LPS. To investigate cytotoxicity Coptidis Rhizoma extract, cell viability was measured by MTT assay. The production of nitric oxide(NO) and inducible nitric oxide synthase(iNOS) was determined in each culture supernatant and mRNA by Griess reaction and RT-PCR. The production of $TNF-{alpha}$ from cells was measured by ELISA. Results : Coptidis Rhizoma extract significantly inhibited LPS-induced NO production in BV2 and RAW264.7 cells. Coptidis Rhizoma extract also greatly suppressed mRNA expression of iNOS in BV2 and RAW264.7 cells activated by LPS. Conclusion : These data suggests that Coptidis Rhizoma extract may have an anti-inflammatory effect through the inhibition of NO production.