A triterpenetricarboxylic acid with a novel 2,3-secolanostane-type framework named lanopropic acid ( 1) was isolated from the aerial parts of Schisandra propinqua var. propinqua. The structure of 1 was elucidated as 2,3-secolanost-9(11),24( Z)-diene-2,3,26-trioic acid on the basis of spectroscopic techniques and X-ray diffraction studies. This is the first report of natural occurrence of 2,3-secolanostane type triterpenoid.