Abstract: The samples pass in a continuous-flow system through a column packed with controlled-porosity glass on which β-glucuronidase is immobilized, and the resulting glucuronic acid is mixed with streams containing NaOH, lucigenin and Na dodecyl sulfate, the chemiluminescent emission intensity being proportional to the free glucuronic acid and therefore to the original glucuronide concentration. Detection limits for phenyl, nitrophenyl, methylumbelliferyl, bromonaphthyl, oestradiol and androsterone glucuronides are from 5 to 10 µM, calibration graphs being rectilinear to 2 mM. The placement of a HPLC Partisil SAX column after the enzyme reactor removes interfering compounds. Results are given for the determination of total glucuronides in urine, and the application of the method to blood is envisaged.