Flowers of Spartium junceum L. (Fabaceae) are used for the treatment of gastric ulcers in Turkish folk medicine. Through bioassay-guided fractionation using chemical and chromatographical means and water immersion and restraint-induced stress ulcer model in rats, a saponin fraction was determined as the potent anti-ulcerogenic ingredient. The active fraction was also highly effective in preventing ethanol- and pyloric ligation-induced gastric lesions as well as inhibiting gastric secretion volume, gastric pH and titratable acidity, but did not affect the hexosamine content of the gastric mucosa. A novel oleanen-type triterpenic saponin, named as spartitrioside, was isolated as the active principle by using chromatographical separation techniques.