Two new sesquiterpenes, named carpabrotalactone A (1) and B (2), together with six known sesquiterpenes, 11(13)-dehydroivaxillin (3), eriolin (4), 2α,5α-dihydroxy-11αH-eudesma-4(15)-en-12,8β-olide (5), (5α)-5-hydroxyasperilin (6), 1α,4α-dihydroxy-guaia-11(13)-ene-12,8α-olide (7) and 4α,5α-dihydroxy-guaia-11(13)-en-12,8α-lactone (8), were isolated from the herbs of Carpesium abrotanoides L.The structures of these sesquiterpenes were elucidated based on spectroscopic anal., and single crystal X-ray diffraction anal.All the compounds exhibited potent cytotoxicity against the ISK, Hela, A549, Sw620, RBE and Caco-2 cell lines, with IC50 values ranging from 7.8-47.4 μM.In addition, compounds 2, 3, 4, 7 and 8 displayed significant anti-influenza A (H1N1) virus activity with IC50 values of 6.2, 11.6, 16.4, 1.3 and 0.4 μM, resp.