Novel CK2 inhibitors among 4-aminothieno[2,3-d]pyrimidines have been identified. The most active compounds obtained in the course of the research are 3-(5-p-tolyl-thieno[2,3-d]pyrimidin-4-ylamino)benzoic acid, 5e (NHTP23, IC50 = 0.01 mM), 3-(5-phenyl-thieno[2,3-d]pyrimidin-4-ylamino)-benzoic acid, 5g (NHTP25, IC50 = 0.065 mM) and 3-(6-methyl-5-phenyl-thieno[2,3-d]pyrimidin-4-ylamino)-bezoic acid, 5n (NHTP33, IC50 = 0.008 mM). The binding mode for compounds in this class with ATP-binding site of CK2 has been proposed (Fig. 1).