In the present study, we investigated the anti-inflammatory effects by Alopecurus aequalis Sobol on the lipopolysaccharide (LPS)-induced nitric oxide (NO) production by RAW 264.7 cell line. Consistent with these observations, DS reduced the LPS-induced expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) at the protein levels in a concentration-dependent manner. In addition, the release of tumor necrosis factor-${alpha}$ (TNF-${alpha}$) and interleukin-6 (IL-6) were also reduced by DS. Moreover, LPS increased expression phosphorylation of $I{kappa}B{alpha}$, but DS showed inhibitory effect by reducing LPS-inducible p-$I{kappa}B{alpha}$ expression level. These results suggest that the down regulation of iNOS, COX-2, TNF-${alpha}$, and IL-6 expression by DS are achieved by the downregulation of NF-${kappa}B$ activity, a transcription factor necessary for pro-inflammatory mediators, and that is also responsible for its anti-inflammatory effects.