Faecal Enterococcus hirae from domestic ducks were studied for their bioactivity to select bioactive strain for more detailed study with its probable use in poultry and also to bring novelty in basic research. After defecation, faeces (n=23, faecal mixture of 40 ducks) were sampled from domestic ducks in eastern Slovakia; birds were aged from eight to 14 weeks. E. hirae strains were identified using Matrix-assisted laser desorption/ionization time-of flight mass spectrometry with a highly probable species identification score (2.300-3.000) or a secure genus identification/ /probable species identification score (2.000-2.299), confirmed by polymerase chain reaction and phenotypization in accordance with the properties for the type strain E. hirae ATCC 9790. Strains were hemolysis negative (γ-hemolysis), and did not have active enzyme stimulating disorders. Enterocin genes were detected in three strains out of seven. Three out of four Enterocin genes were detected in Kč1/b (Ent A, P, L50A); the most frequently detected was the Ent P gene. The strains inhibited indicator strains E. faecalis, listeriae, but also Escherichia coli and Buttiauxiella strains. Lactic-acid producing E. hirae were mostly susceptible to antibiotics. Based on parameter evaluation, E. hirae Kč1/b, Kč6 can be additionally studied to select the type of bioactive substance.