Cornusiin A (1), cornusiin B (2) and cornusiin C (3), new dimeric monomeric and trimeric hydrolyzable tannins, were isolated from the fruits of cornus officinalis (Cornaceae). Their structures, including the orientation of the valoneoyl group in 1 and 3, were established on the basis of chemical and spectroscopic data. 2, 3-Di-O-galloyl-D-glucose (7), 1, 2, 3-tri-O-galloyl-β-D-glucose, 1, 2, 6-tri-O-galloyl-β-D-glucose, 1, 2, 3, 6-tetra-O-galloyl-β-D-glucose, gemin D (5), isoterchebin, tellimagrandin I (6) and tellimagrandin II were also isolated from the fruits. The orientation of the valoneoyl group in camptothin A (14) and that in camptothin B (15), which had been isolated from Camptotheca acuminata (Nyssaceae), were also determined based on that in 1.