A new flavonoid, 5,7,3'-trihydroxy-6-C-beta-D-digitoxopyranosyl-4'-O-beta-D-glucopyranosyl flavonoside (1), along with four known flavonoids 5,7,4'-trihydroxy-3',5'-dimethoxy flavone (2), 5,3',4'-trihydroxy-7-O-beta-D-glucopyranosyl flavonoside (3), 5,4'-dihydroxy-3',5'-dimethoxy-7-O-beta-D-glucopyranosyl flavonoside (4), 5,3',4'-trihydroxy-6-C-[beta-D-glucopyranosyl-(1 --> 6)]-beta-D-glucopyranosyl flavonoside (5) were isolated from 95% EtOH extract of the leaves of Pleioblastus argenteastriatus. Their structures were determined on the basis of spectroscopic techniques and chemical methods.