A series of polyanionic compounds was synthesized and evaluated for their activity against human immunodeficiency virus (HIV-1, HIV-2) and various other RNA and DNA viruses. Several compounds, i.e., 2p, 3p, 8p, 13p, 14p, 15p, 17p, 18p, and 19p, proved active against HIV-1 within the concentration range of 0.1-3 micrograms/mL while not being toxic to the host cells (CEM, MT-4) at concentrations up to 100 micrograms/mL or higher. As a rule, these polyanionic compounds proved also active, albeit at somewhat higher concentrations than those required for HIV-1 inhibition, against a number of other enveloped viruses, including HIV-2, human cytomegalovirus, influenza A virus, respiratory syncytial virus, and arenaviruses (Junin and Tacaribe). Among the most potent HIV-1 inhibitors ranked compounds 18p and 19p, the sodium salts of N-methylamides obtained by polymerization of monomers prepared starting from 10-undecenoyl chloride and omega-aminoalkanoic acids.