In our continuing search to discover bioactive compounds from medicinal plants, a methanolic extract of Verbascum songaricum collected in Kazakhstan was investigated. Activity-guided fractionation of the extract prepared from the plant, using a sensitive assay to monitor DNA polymerase reactions, resulted in the isolation of two known phenylethanoid glycosides, poliumoside (1) and verbascoside (2). Glycoside 1 was shown to inhibit mammalian DNApolymerases α,β,δ and ε with IC_<50> values of 42, 23, 35 and 9 μM, respectively, while those of glycoside 2 were all more than 100 μM.