TESTICULAR hyaluronidase has frequently been used for the analysis of hyaluronic acid and chondroitin sulphate despite the known gross inhomogeneity of the enzyme preparation1,2. Known contaminants include acid phosphatase, esterase, β-galactosidase, β-glucuronidase, glucosidases and N-acetylglucosaminidases3. To our knowledge, there has been no previous report of contamination of hyaluronidase with ribonuclease.