The absolute configuration of the guaiane-type sesquiterpene lactone 8-epiisolippidiol-3-O-beta-D-glucopyranoside, isolated from plants of the genus Crepis, and the predominant solution-state conformation in CD3OD were determined by comparison of experimental and calculated VCD spectra. It has been found that the reported stereostructure of the compound corresponds to its absolute configuration. (c) 2007 Elsevier B.V. All rights reserved.