The present study was conducted to evaluate the effect of Yongdamsagantang (YST) on the regulatory mechanism of cytokines and nitric oxide (NO) for the immunological activities in RAW 264.7 cells. After the treatment of YST water extract, cell viability was measured by MTT assay, and NO production was monitored by measuring the nitrite content in culture medium. Inducible nitric oxide synthase (iNOS) and phospholylation of inhibitor of nuclear factor kappa B alpha ($p-I{kappa}B{alpha}$) were determined by Immunoblot analysis, and levels of cytokine were analyzed by sandwich immunoassays. Results provided evidences that YST inhibited the production of NO. iNOS, and interleukin-6, and the activation of $p-I{kappa}B{alpha}$ in RAW 264.7 cells activated with lipopolysaccharide. These findings showed that YST could have some anti-inflammatory effects which might play a role in therapy in Gram-negative bacterial infections.