A new triterpenoid saponin, 3-O-[beta-D-galactopyranosyl-(1 --> 3)-O-beta-D-xylopyranosyl-(1 --> 4)-O-alpha-L-rhamnopyranosyl]-oleanolic acid; has been isolated from the seeds of Lactuca scariola. Its structure was determined by various spectral analysis and chemical degradations. This compound