Chemical constituents of ethyl acetate extract of Sapium sebiferum leaves were isolated and purified by various chromatographic methods, including column chromatographies over silica gel, macroporous adsorption resin, and Sephadex LH-20, as well as preparative TLC and semi preparative HPLC. As a results, 15 compounds were separated from Sapium sebiferum leaves and their structures were examined by spectral analysis including NMR and MS data and identified as( + )-(7R,7'R,7"S,7'"S,8S,8'S,8"S,8'"S)-4", 4"'-dihydroxy-3,3',3",3',5,5'-hexamethoxy-7,9';7',9-diepoxy-4,8";4',8'"-bisoxy-8,8'-dineo-lignan-7",7"',9",9"'-tetraol(1) ,1-(4'- hydroxy-3'-methoxyphenyl)-2-[4"-(3-hydroxypropyl) -2", 6"-dimethoxyphenoxy] propane-1, 3-diol (2), Thero-2, 3-bis-(4-hydroxy-3- methoxypheyl)-3-methoxy-propanol(3) , threo-5-hydroxy-3,7-dimethoxyphenyl propane-8,9-diol (4), boropinol B (5), threo-8S-7-methoxysyringylglycerol(6), 5-hydroxymethylfurfural(7), 5-( methoxy-methyl)-1H-pyrrole-2-carbaldehyde (8), quercetin (9) , kaempferol (10), ethyl gallate(11), coniferaldehyde(12), vanillin(13), 7-hydroxy-6-methoxy-2H-1-henzopyran-2-one(14),and 1-heptacosanol (15). All compounds except for compounds 9-11,14 were separated from this plant for the first time.