Four new dimeric phthalides, angesinenolides C−F ( 1 − 4 ), along with three known ones, were isolated from the roots of Angelica sinensis. Their structures were determined by means of HRMS and NMR experiments. The structures of compounds 1 and 3 were confirmed using X-ray crystallographic data. All isolated compounds were tested for activities on the inhibition of COX-2 enzyme in vitro . Compounds 1 – 6 exhibited inhibitory activity against COX-2 with IC 50 values ranging from 29.32 ± 0.07 to 137.91 ± 0.24 μ M. [ABSTRACT FROM AUTHOR]