We have explored analogs of 2'-5'-linked andeylic acid trimer (2-5A): 3'-O-methylated 2-5A, 2'-end modified adenylate trimer with deoxyadenosine or araadenine, methyl phosphonate and methyl phosphorotriester analogs as potential antiviral agents. For the treatment of virus infections, 2-5A and its analogs may serve in lieu of interferon, however, the use of 2-5A has two serious limitations: it is presumed to be impermeable to most cells, and moreover, cellular enzymes rapidly degrade it. Methylated analogs of 2-5A core strongly inhibited virus growth when added directly to cells in culture. 2'-End modified adenylate trimer with araadenine also inhibited virus growth, however, neither 2-5A nor other analogs showed any significant antiviral activity. The inhibition of virus growth was not due to the toxic effect of these compounds on cell growth as they had no inhibitory effect on the growth of uninfected cells.