In an attempt to find bioactive natural products with an anti-inflammatory activity, we evaluated the effects of the methanol extract of Fomes fomentarius (MEFF) on in vivo anti-inflammatory and anti-nociceptive activities. MEFF (50, 100 mg/kg/d, p.o.) reduced acute paw edema induced by carrageenin in rats, and showed MEFF analgesic activity, as determined by an acetic acid-induced writhing test and a hot plate test in mice. To investigate the mechanism of the anti-inflammatory action of MEFF, we examined the effect of MEFF on lipopolysaccharide (LPS)-induced responses in murine macrophages cell line RAW 264.7. MEFF potently inhibited the production of nitric oxide (NO), prostaglandin E2 (PGE2), and tumor necrosis factor-alpha (TNF-alpha) in LPS-stimulated RAW 264.7 macrophages. Consistent with these observations, inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) levels were reduced by MEFF in a dose-dependent manner. Furthermore, MEFF suppressed nuclear factor-kappaB (NF-kappaB) activation in LPS-stimulated RAW 264.7 macrophages. These findings suggest that the anti-inflammatory and anti-nociceptive properties of the methanol extract of MEFF may result from the inhibition of iNOS and COX-2 expression through the down-regulation of NF-kappaB binding activity.