From the methanolic extract of the roots of Sonchus asper, two new sesquiterpene glucosides, together with two known sesquiterpene glucosides and a known aglycone were isolated. Structures were identified as 11beta,13-dihydrourospermal A, 15-O-beta-D-glucopyranosyl-11beta,13-dihydrourospermal A, 15-O-beta-D-glucopyranosylurospermal A, 15-O-[6'-(p-hydroxyphenylacetyl)]-beta-D-glucopyranosylurosperm al A and 14-O-methylacetal-15-O-[6'-(p-hydroxyphenylacetyl)]-beta-D-+ ++glucopyranosylurospermal A, by spectroscopic means.