Antagonistic activity of Enterococcus faecium L3 against groups A, B, C, D and G of streptococci was evaluated. L3 was more active against streptococci from groups A and C. Enterococcal strains were most resistant. Peptide fractions (3-5 kDa) isolated from supernatant of L3 possess distinctive antibacterial effect. PCR analysis of L3 DNA revealed genes for enterocins (entA, entB and genes responsible for their expression). Antibacterial activity of E. faecium L3 may be associated with enterocin A and B production.