In order to establish the anti-inflammatory cellular mechanism of the paeony root(Paeonia lactiflora, Pall, Paeoniaceae), the constituents including paeoniflorin, albiflorin, (+)-catechin, paeonol, benzoic acid and methyl gallate were evaluated for their effects on arachidonate and NO metabolism. Among the compounds tested, only paeonol weakly inhibited cyclooxygenase-2-mediated $PGE_2$ production from LPS-treated RAW 264.7 cells. (+)-Catechin and methyl gallate weakly inhibited inducible nitric oxide synthase-mediated NO production from the same cell line. In particular, methyl gallate significantly inhibited 5-lipoxygenase from RBL-l cells with an $IC_{50}$ of 8.4 ${mu}M$. These results suggest that the inhibition of these components on arachidonate and NO metabolism may contribute at least in part to anti-inflammatory mechanism of the paeony root.