The photochemical study of Viscum album (Loranthaceae) led to the isolation of twelve compounds, lupeol (1), betulonic acid (2), betulinic acid (3), terminic acid (4), ursolic acid (5), $eta$-sitosterol (6), $alpha$- spinasterol (7), oleanolic acid (8) , 5-hydroxy-1- (4′-hydoxyphenyl) -7- (4"-hydroxyphenyl) -hepta-1- en-3-on (9), 2′-hydroxy -4′, 6′- dimethoxychalcone -4-O-glycoside (10) ,2′-hydroxy-4′, 6′-dimethoxychalcone -4-O- [apiosal(1longrightarrow12)]glucoside (11) and syringin (12). Their structures were established by chemical and spectroscopic methods. The cytotoxicity of the isolated compounds was evaluated by sulforhodamine B assay against five cultured human tumor cell lines.