Four new stilbene derivatives, polygonumosides A-D (1-4), were isolated from the processed roots of Polygonum multiflorum. Their structures were elucidated by spectroscopic analysis, including 1D and 2D NMR and ECD. Polygonumosides A (1) and B (2), possessing an unprecedented tetracyclic skeleton, were assigned as 2S- and 2R-2-(4-hydroxyphenyl)-9,10,11-trihydroxy-2H-benzo[c]furo[2,3-f]chromen-7(3H)-one-4-O-β-d-glucopyranosides, respectively, while polygonumosides C (3) and D (4) were assigned as a pair of diastereomeric stilbene glucoside dimers.