This research is performed to obtain positive evidences of Mori cortex, a kind of oriental medicinal herbs, in the cellular levels. The extracts of M. cortex have shown anti-inflammatory effects against cutaneous inflammation and clinical effects on pulmonary asthma and congestion in oriental medicine. Thus BV2 cells were chosen because microglia are considered as the main immunocompetent cells in the central nervous system. Lipopolysaccharide (LPS)-induced microglial activation of cultured BV2 cells and subsequent release of nitric oxide (NO) and Prostaglandin E2 (PGE2) were effectively suppressed by methylene chloride extract of Morus alba L. (MEMA). From the inflammation-mediated mRNA and protein analyses, we showed that inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), interleukin-$1{eta}$ (IL-$1{eta}$) and tumor necrosis alpha (TNF-${alpha}$) induced by LPS were markedly decreased by MEMA treatment. From the observation of nuclear factor-kB (NF-${kappa}B$) which is controlling and mediating inflammation through COX-2 and iNOS, there showed that p65, a subunit of NF-${kappa}B$, was increased in nuclear and $I{kappa}B$, a competitor of NF-${kappa}B$, was recovered in cytosol after MEMA treatment. These are corresponding with results of iNOS, COX-2, IL-$1{kappa}$ and TNF-${alpha}$, and confirm some suppressive effect against transcriptional activation of NF-${kappa}B$. In conclusion, the anti-inflammatory action of M. cortex against BV2 microglia cells is expected to protect nerve tissues through suppression of neuronal inflammation in various neurodegenerative diseases.