The synthesized fused 1,2,4-triazines were tested for their potential antimicrobial activity resulting from the literature data. 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 that these compounds in examined concentrations 100 mg ml(-1) and 200 mg ml(-1) had no influence on the growth of microorganisms tested. The microbiological screening tests afforded to limit the possible biological spectrum of activity of tested compounds.