A new megastigmane glycoside, galloyl linarionoside A (1), together with 13 known compounds (2-14) were isolated from the aerial parts of Aceriphyllum rossii ENGLER. (Saxifragaceae). The chemical structures of the isolated compounds were established mainly by using nuclear magnetic resonance spectra, mass spectrometry, and modified Mosher's method. Among the isolates, compounds 4, 5, 6 and 7 showed potent inhibitory activity against the lipopolysaccharide-induced nitric oxide production in RAW264.7 macrophage cells with IC50 values of 12.5, 9.5, 10.5 and 9.3 µM, respectively. The anti-inflammatory effect of compound 7 was accompanied by dose-dependent decreases in the production of inducible nitric oxide synthase and cyclooxygenase-2 proteins not in the inhibitor kappa B (IκB)-dependent nuclear factor-kappa B activation.