In continued studies on cultivated Korean rhubarb rhizomes, three additional stilbene compounds were isolated from water extract by column chromatographic separation using Sepha dex LH-20, ODS-gel. Compound I, desoxyrhapontigenin(3,5-dihydroxy-4`-methoxystilbene), Compound II, rhapontigenin(3,3`,5-trihydroxy-4`-methoxystilbene), and compound III, piceatannol(3,3`,4`,5-tetrahydroxystilbene) were elucidated based on physico-chemical and spectroscopic evidences(UV, IR, $^1H$-NMR, $^13C$-NMR and Mass).