|5'-nucleotidases have been described as virulence factors in various pathogenic bacteria. The aim of this examination was to investigate a possible influence of a 5'-nucleotidase activity on the virulence of Streptococcus pyogenes. Strains of serotypes M6, M18 as well as M49 were used. Especially, the ability to form biofilms, to survive in human blood and plasma, and in the Galleria mellonella infection model was investigated. The data from this study indicate that the 5'-nucleotidase has no significant effect on the virulence of S.pyogenes.