Korean Marine Plants (KMU-4, 6, 7) obtained from an herb which widely used in medicine for the treatment of a variety of pathologies. In this study, using mouse peritoneal macrophages, we have examined whether KMU-4, 6, 7 affects nitric oxide (NO) and COX-2 induced IFN-$gamma$ and LPS and cell viability. KMU-6 inhibits IFN-$gamma$ and LPS-induced NO. We found that KMU-6 had a little effect on COX-2 expression. These finding means that KMU-6 can be used in controlling macrophages mediated inflammatory disease. The present results indicate that KMU-6 has an inhibitory effect on the production of NO through down-regulation of COX-2 expression in LPS stimulated mouse peritoneal macrophages.