SUMMARY:Proteinase produced by Group A streptococci was associated with a decrease in hyaluronidase production which was not related to any other known environmental condition. The concentration of proteinase which was correlated with decreased hyaluronidase production was constant for a given strain. Inactive polysaccharidase components in cell-free filtrates were converted to active form by a number of different agents, namely, sodium sulphite, zinc and calcium ions, autoclaved broth and pantothenic acid. Bacterial dextran, pectin and inulin were depolymerized by cell-free filtrates and by partially purified enzymes derived from Type 4, Type 22 and Type 2 strains. ' Depolymerase ' was associated with hyaluronidase and amylase in biologically active material prepared by fractional precipitation.