Abstract:Abstract From the roots of Peucedanum decumbens Mexiam (Umbelliferae), a new coumarin decumbensol (1) was isolated and the structure was established as cis-2‘ - (1"-methyl, 1"-sencioyloxy-ethyl) -3‘ -hydroxy linear-dihydr-furanocoumarin by spectroscopic evidence. Five known coumarins, angenomalin( 2 ),columbianadin (3), bergapten( 4 ), umbelliferone( 5 ) and nodakenin( 7 ) were isolated together with ferulic acid(6), stearic acid, lignoceric acid, β-sitosterol and γ-sitosterol.