A new monoterpene, (-)-10-hydroxydihydroactinidiolide (1), along with two known monoterpenes, loliolide (2) and (+)-isololiolide (3), three known megastigmanes, 3 alpha-hydroxy-5 beta,6 beta-epoxy-beta-ionone (4), 3 alpha-hydroxy-5 alpha,6 alpha-epoxy-beta-ionone (5), and (+)-dehydrovomifoliol (6), a eudesmane-type sesquiterpene, 4 alpha-hydroxy-4 beta-methyldihydrocostol (7), a monoterpene, 8-hydroxycarvotanacetone (8), two flavonoids, chrysoeriol (9) and apigenin (10), and a phenylpropanoid, 3-(4-hydroxyphenyl)-1-propanol (11), were isolated from the whole plant of Achillea millefolium. The structure of compound 1 was identified according to spectroscopic data of HRMS and NMR, and its absolute configuration was assigned by 13C NMR calculations with DP4+ probability analyses and ECD calculations. The absolute configuration of compound 6 was determined by ECD calculations. Compounds 3, 6, 9 and 10 could dose-dependently inhibit the NO release in LPS-induced RAW264.7 cells. image