Extraction of the roots of Baptisia australis afforded a new triterpenoid saponin, baptisiasaponin I together with kaikasaponin III. The structure of baptisiasaponin I was elucidated as 3-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-xylopyranosyl- (1-->2)-beta-D-glucuronopyranosyl sophoradiol on the