The synthesized imidazo[2,1-c]triazines were tested for their antimicrobial activity. Microbiological screening tests conducted in relation to 54 strains of Gram-positive and 52 strains of Gram-negative bacteria, 6 strains of yeast-like fungi and 3 strains of moulds showed significant activity of compound 19 against 52 Gram-negative bacterial strains. This compound was active against 16 strains of Escherichia coli, 12 strains of Pseudomonas, 10 strains of Proteus spp., 8 strains of Klebsiella pneumoniae and 6 strains of Enterobacter aerogenes in the examined concentrations (100 microg ml(-1) and 200 microg ml(-1)).