Seungma-galgeun-tang (SGT) has been used for treatment of chronic diseases in the folk medicine recipe. Since nitric oxide (NO) is one of the major inflammatory parameters, we first studied the effects of SGT on NO production in lipopolysaccharide (LPS)-stimulated BV-2 microglia. SGT inhibited the secretion of NO in BV-2 microglia, without affecting cell viability. The protein level of inducible nitric oxide synthase (iNOS) was decreased by SGT and SGT also inhibited production of PGE(2) and expression of Cox-2. Proinflammatory cytokines, such as TNF-alpha, IL-1beta and IL-12, were inhibited by SGT in a dose-dependent manner and SGT blocked the activation of NF-kappaB, which was considered to be a potential transcription factor for the expression of iNOS, COX-2 and proinflammatory cytokines. SGT also blocked the degradation of IkappaB and activation (decrease of cytosolic p65) of NF-kappaB, p65. These results suggest that SGT could exert its anti-inflammatory actions by suppressing the synthesis of NO through inhibition of NF-B activity.