To assess the anti-inflammatory activity of constituents from the rhizomes of Anemarrhena asphodeloides, (-)-nyasol {cis-hinokiresinol, 4,4-[1Z,3R]-3-ethenyl-1-propene-1,3-diyl]bisphenol} was isolated and its anti-inflammatory activity was examined in lipopolysaccharide (LPS)-treated RAW 264.7 cells and A23187-treated RBL-1 cells. In vivo activity was measured using carrageenan-induced paw edema assay. At > $1;{mu}M$, (-)-nyasol significantly inhibited cyclooxygenase-2 (COX-2)-mediated $PGE_2$ production and inducible nitric oxide synthase (iNOS)-mediated NO production in LPS-treated RAW 264.7 cells, a mouse macrophage-like cell line, but did not affect the expression levels of COX-2 and iNOS. (-)-Nyasol also inhibited 5-lipoxygenase (5-LOX)-mediated leukotriene production in A23187-treated RBL-1 cells. Furthermore, (-)-nyasol potently inhibited carrageenan-induced paw edema in mice (28.6-77.1% inhibition at 24-120 mg/kg). Therefore, (-)-nyasol is a potential new lead compound and may contribute to the anti-inflammatory action of A. asphodeloides, possibly by inhibiting COX-2, iNOS and 5-LOX.