Woodfruticosin (I), a new dimeric tannin having an inhibitory activity against DNA topoisomerase 11,was isolated from the methanol extract of Woodfordia fruticosa Kurz (Lythraceae) and its structure was determined by the use of 2D NMR spectroscopy including HMQC and HMBC techniques. As a art of our studies on biologically significant substances from medicinal plants in Nepal,' P we have isolated a new dimeric hydrolysable tannin, named woodfruticosin (J), from the leaves of Woodfordia fruticosa Kurz (Lythraceae) 2) and found that it has an inhibitory activity against DNA topoisomerase II. 3) This paper describes the isolation and structure elucidation of this new tannin. The methanol extract of dried leaves (590 g) of W. fruticosa, collected in Nepal, was extracted with chloroform and then with ethyl acetate. The insoluble residue was roughly separated by Iatrobeads column chromatography with 25% MeOH/CHC13, 50% MeOH/CHC13, and MeOH. The MeOH eluate was further separated by a combination of chromatographies over Diaion HP-20 and Sephadex LH-20 to give woodfruticosin (I)(750 mg). Woodfruticosin (I), a light brown powder, C75H5204B, 4, [$3 t114.5" (acetone),showed UV absorptions (MeOH) at 219 and 271 nm (log E: 5.07 and 4.77) and IR absorptions (KBr)