We investigated whether an aqueous extract of Chong-Myung-Tang inhibits secretion of tumor necrosis factor-a (TNF-α) from primary cultures of mouse astrocytes. Chong-Myung-Tang dosedependently inhibited the TNF-α secretion by astrocytes stimulated with substance P (SP) and lipopolysaccharide (LPS). Interleukin-1 (IL-1) has been shown to elevate TNF-α secretion from LPS-stimulated astrocytes while having no effect on astrocytes in the absence of LPS. We therefore investigated whether IL-1 mediated inhibition of TNF-α secretion from astrocytes by Chong-Myung-Tang. Treatment of Chong-Myung-Tang to astrocytes stimulated with both LPS and SP decreased IL-1 secretion. Moreover, incubation of astrocytes with IL-1 amtobody abolished the synergistic cooperative effect of LPS and SP. These results suggest that Chong-Myung-Tang may inhibits TNF-α secretion by inhibiting IL-1 secretion and that Chong-Myung-Tang has a antiinflammatory activity in the central nervous system.