Substrate specificities of three viral replicative polymerases of different origins (HIV reverse transcriptase, hepatitis C virus RNA polymerase, and herpes virus DNA polymerase) towards 2'F-NTP were studied. Activated DNA, polyA-oligoUs and (2'F-A)20-oligoU6-complexes were used as templates. It was shown that all DNA polymerases studied can incorporate 2'F-NMP into the 3'-end of primer-template complexes. HIV reverse transcriptase and herpes virus DNA polymerase can elongate synthesis with both dNTP and 2'F-NTP. Homopolymer (2'F-A)20 can serve as a template for polymerization of both UTP and 2'F-UTP,-catalyzed by hepatitis C virus polymerase although with efficacy about 5 to 10-fold lower in comparison with natural primertemplate complex. Pyrophosphorolysis reaction of 2'F-CMP residue at 3'-end of primer catalyzed with HIV reverse transcriptase is going by two orders of magnitude less effective if compared with natural dNMP residue at the same system.