A new polyacetylenic compound, araliadiol, was isolated from the leaves of Aralia cordata Thunb. (Araliaceae). The structure of araliadiol was determined to be 3( S),8( R)-pentadeca-1,9( Z)-diene-4,6-diyne-3,8-diol by MS, NMR, IR, and UV spectroscopic analysis as well as Mosher ester reaction.