Korean Sophora japonica has been found to posses an anti-inflammatory activity. In this study, Korean Sophora japonica extract, rutin, was used to know whether rutin inhibits to produce inflammatory mediators NO and TNF-α from the mouse peritoneal macrophages that were treated an inflammatory agent LPS. The rutin-1 hr pretreated macrophages were incubated with LPS for 0.5~5 hrs, and then collected the supernatant and the cell lysate for measurements of the level of iNOS, NO, TNF-α mRNA, TNF-α, and p-NF-κB. Minimal and maximal effective doses of the rutin on them were 1 and 100 ㎍/㎖, respectively. The maximal effective dose of rutin certainly inhibted the productions of iNOS, NO, TNF-α mRNA, TNF-α and p-NF-κB from the LPS-treated macrophages (p less than 0.0001). Its ED∧50 for inhibition of TNF-α mRNA and p-NF-κB was 5 ㎍/㎖, and for iNOS, NO, and TNF-α was 10 ㎍/㎖. The rutin did not have any cytotoxic effect. As the results, the Sophora japonica rutin could be a good candidate for an anti-inflammatory action.