This study was designed to identify the effects of Polygoni cuspidati Radix(PCR) on the generation of superoxide anion radicals (ㆍO₂<SUP>-</SUP>), nitric oxide (NO), peroxynitrite (ONOO<SUP>-</SUP>) in the renal epithelial cells of mouse(LLC-PK₁). The effects of PCR on the expression of inflammation-related proteins, IKK-α, phospho-IκB-α, NF-κB (p50, p65), COX-2, iNOS, IL-1β, VCAM-1, were examined by western blotting. For this study, the fluorescent probes, namely dihydrorhodamine 123 (DHR 123), 2’,7’-dichloro dihydrofluorescein diacetate (DCFDA), 4,5-diaminofluorescein (DAF-2) were used. Protein expression levels of IKK-α, phospho-IκB-α, NF-κB (p50, p65), COX-2, iNOS, IL-1β, VCAM-1 were assayed by western blot. PCR reduced H₂O₂-induced cell death dose-dependently. It inhibited the generation of ㆍO2-, NO, ONOO- and PGE2 in the H2O2-treated LLC-PK1 cells in vitro. PCR inhibited the espression of IKK-α, phospho-IκB-α, COX-2, iNOS, IL-1β and VCAM-1 genes by means of decreasing the NF-κB activation. These results suggest that PCR is an effective NO, ㆍO₂<SUP>-</SUP><SUP></SUP>, ONOO<SUP>-</SUP> scavenger, and this substance recommended to be applied in treatment for the inflammatory process and inflammation-related disease.