Twelve compounds were isolated from Winged Sumac (Rhus copallinum) fruit and their structures were elucidated on the basis of NMR and mass spectral data. The isolates included a new galloyl derivative, (R)-galloyl malic acid dimethyl ester (1), and eleven known compounds, gallic acid (2), methyl gallate (3), glucogallin (4), methyl m-digallate (5), methyl p-digallate (6), quercetin (7), myricetin (8), rhamnazin (9), kaempferol (10), betulinic acid (11), and oleanolic acid (12). All of the compounds were evaluated for antiproliferative effects against human colon tumorigenic (HCT-116, Caco-2) and nontumorigenic (CCD18-Co) cell lines.