Three new dimeric hydrolyzable tannins, woodfordins A, B and C, along with seven known hydrolyzable tannins, including oenotheinB, a dimer exhibiting marked host-mediated antitumor activity, were isolated from an Indonesian crude drug, Sidowayah [dried flowers of Woodfordia fruticosa (L.) Kurz (Lythraceae)]. The structures of the new tannins were elucidated based on chemical and spectral evidence