Two new sesquiterpene lactone xylosides, derivatives of the guaianolides 9alpha-hydroxyleucodin and 9alpha-hydroxy-11,13-dehydroleucodin, were isolated from roots of Lactuca triangulata. Their structures were established on the basis of (1)H and (13)C NMR spectra, 2D NMR (HMQC, HMBC, COSY, NOESY)