A new triterpenoid, saponin hehuanoside A, was isolated together with the known triterpenoid saponins 2, 3, and 4 from the stem bark of Albizia julibrissin. With the help of chemical and spectral analyzes (IR, MS, 1D-NMR, and 2D-NMR), the structure of the new triterpenoid saponin was elucidated as 21-O-[(6S)-2-trans-2,6-dimethyl-6-O-beta-d-quinovopyranosyl-2,7-octadienoyl]-3-O-beta-d-xylopyranosyl-(1 --> 2)-beta-d-fucopyranosyl-(1 --> 6)-beta-d-2-deoxy-2-acetamidoglucopyrasyl acacic acid 28-O-alpha-l-arabinofuranosyl-(1 --> 4)-[-beta-d-glucopyranosyl-(1 --> 3)]-alpha-l-rhamnopyranosyl-(1 --> 2)-beta-d-glucopyranosyl ester (1). Three known triterpenoid saponins 2-4 were identified on the basis of spectroscopic data.