A forecast on the extract components of Eucalyptus dundasii leaves. The leaves of Eucalyptus dundasii contain a large amount of a substance that we previously referred to as a third glycoside found in Eucalyptus sideroxylon (E. sideroxylon). This time, we extracted it purely as an acetate (melting point 152-3°). Based on NMR, IR, UV spectra, and elemental analysis, the original substance is considered to be a glycoside of 3,5,3',4'-tetrahydroxystilbene. As a result of hydrolysis, 3,5,3',4'-tetrahydroxystilbene and glucose were identified, and we have named the original glycoside 'astringin.'