In the present study, we investigated the anti-inflammatory effects by Alopecurus aequalis Sobol on thelipopolysaccharide (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) atthe protein levels in a concentration-dependent manner. In addition, the release of tumor necrosis factor-α (TNF-α) andinterleukin-6 (IL-6) were also reduced by DS. Moreover, LPS increased expression phosphorylation of IκBα, but DS showedinhibitory effect by reducing LPS-inducible p-IκBα expression level. These results suggest that the down regulation of iNOS,COX-2, TNF-α, and IL-6 expression by DS are achieved by the downregulation of NF-κB activity, a transcription factornecessary for pro-inflammatory mediators, and that is also responsible for its anti-inflammatory effects.