Antimicrobial copolymers bearing quaternary ammonium. and phosphonium salts based on a copolymer of glycidyl methacrylate and 2-hydroxyethyl methacrylate were synthesized. Poly(glycidyl methaerylate-co-2-hydroxyethyl methacrylate) was modified for the introduction of chloromethyl groups by its reaction with chloroacetyl chloride. The chloroacetylated copolymer was modified for the production of quaternary ammonium or phosphonium. salts. The antimicrobial activity of the obtained copolymers was studied against gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Shigella sp., and Salmonella typhae), gram-positive bacteria (Bacillus subtilus and B. cercus), and the fungus Trichophyton rubrum by the cut-plug method. The results showed that the three copolymers had high antimicrobial activity. A control experiment was carried out on the main polymer without ammonium or phosphonium groups. The copolymer bearing quaternary salt made from tributyl phosphine was the most effective copolymer against both gram-negative and grain-positive bacteria and the fungus T. rubrum. The diameters of the inhibition zones ranged between 20 and 60 min after 24 h.