Abstract: This invention relates to new nucleotide analogues and solves the technical problem of their use as biologically active compounds. The subject of this invention are N-(2-phosphonylmethoxyethyl) and N-(3-hydroxy-2-phosphonylmethoxypropyl) derivatives of pyrimidine and purine bases, easily accessible from heterocyclic bases andd their N-(2-hydroxyethyl) or N-(2,3-dihydroxypropyl) derivatives. Some of the compounds, according to this invention, exhibit a marked antiviral activity or can be converted into such active compounds by chemical transformations.