The diarylheptanoid (S)-1,7-bis-(4-hydroxyphenyl)-heptan-3-one-5-O-beta-D-xylopyranosi de, and two known compounds, 1,7-bis-(3,4-dihydroxyphenyl)-heptan-3-one-5-O-beta-D-glucopyranos ide and platyphylloside were isolated from Alnus rubra bark. Structures were established by application of