We investigated whether an aqueous extract of Rehmannia glutinosa steamed root (RGAE) inhibits secretion of inflammatory cytolanes from primary cultures of mouse astrocytes. RGAE dose-dependently inhibited the $TNF-{alpha}$ secretion by astrocytes stimulated with substance P (SP) and lipopolysaccharide (LPS). Interleukin-1 (IL-1) has been shown to elevate $TNF-{alpha}$ secretion from LPS-stimulated astrocytes while having no effect on astrocytes in the absence of LPS. We therefore also investigated whether IL-1 mediated inhibition of $TNF-{alpha}$ secretion from primary astrocytes by RGAE. Treatment of RGAE to astrocytes stimulated with both LPS and SP decreased IL-1 secretion to the level observed with LPS alone. Moreover, incubation of astrocytes with IL-1 antibody abolished the synergistic cooperative effect of LPS and SP. These results suggest that RGAE has an antiinflammatory activity on the central nervous system curing some pathological disease states.