The newly synthesized antimicrobial copolymers i.e. [poly N-vinylpyrrolidone -block- poly ε-caprolactone -ɷ-hydroxyethylmethacrylate] (KFB), [(poly N-vinylpyrrolidone -block- poly ε-caprolactone -ɷ-hydroxyethylmethacrylate) -graft- poly-4-Vinylpyridine] (KFC) and [(poly N-vinylpyrrolidone -block- poly ε-caprolactone -ɷ-hydroxyethylmethacrylate) -graft- poly-4-Vinylpyridine octyl bromide] (KFCQ), were tested in vitro, using diffusion disc method (MDD) against two microbial strains: gram-positive bacteria Staphylococcus aureus ATCC 25923 (S. aureus) and gram-negative bacteria Escherichia coli ATCC 25922 (E. coli). Good antibacterial activities were observed for all tested copolymers. It was demonstrated that gram-positive bacteria were more sensitive than gram-negatives, and KFCQ agent was more active than KFB and KFC.