Taraxci Herba (TH; Pogongyoung in Korean) has been used in traditional oriental medicine for the treatment of various ailments. The biological activity of this plant is not yet evaluated systematically. This study was conducted to evaluate the inhibitory effects of TH on the production of nitric oxide (NO) and the expression of inducible nitric oxide synthase (iNOS) in lipopolysaccharide (LPS)-activated Raw264.7 cells. The aim of the present work is to investigate a potential anti-inflammatory activity of TH. The Raw264.7 cells were cultured in DMEM medium for 24 h. After serum starvation for 12 h, the cells were treated with TH for 1 h, followed by stimulating NO production with LPS ($2{mu}g/ml$). As result of this study, TH inhibited the levels of NO, PGE2, $TNF-{alpha}$, IL-6 and $IL-1{eta}$, and the expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) activated by LPS. These inhibitory effects were mediated though the inhibition of phosphorylation of inhibitory kappa B ($I{kappa}B$). These findings showed that TH could have some anti-inflammatory effects.