Abstract: AIMThe anti-gastric ulcer constituents from the roots of Crepis napifera (Franch) Babc (Compositae) were studied. METHODSSolvent partition, Si gel and Rp-18 column chromatography, crystallization and spectral methods were used to extract, isolate and identify two compounds. The activity of compound 1 was tested on the mouse stomach by determining the effect on aspirin-induced gastric lesions and on histamine-stimulated gastric acid secretion. RESULTSTwo sesquiterpene lactone glycosides, taraxinic acid-1′-O-β-D-glucopyranoside (1) and 11,13-dihydro-taraxinic acid-1′-O-β-D-glucopyranoside (2) were obtained. Compound 1 at the dose of 80 mg·kg^-1 po inhibited significantly the development of aspirin-induced gastric lesions in the rat and at an iv dose of 70 mg·kg^-1 did not affect histamine-stimulated gastric acid secretion in the lumen-perfused rat stomach. CONCLUSIONCompound 1 is the active component of the plant which protects gastric mucosa and exhibits anti-gastric ulcer action.