Seven new tannins, elaeagnatins A-G, have been isolated from the leaves of Elaeagnus umbellata (Elaeagnaceae) together with fifteen known tannins and related polyphenols, and their structures have been characterized as monomeric and dimeric C-glucosidic ellagitannins on the basis of spectral and chemical evidence. Elaeagnatins B, C and F are the first dimers composed of C-glucosidic monomer and ellagitannin monomer with a gluconic acid core.