Determination of B-glucuronidase activity was carried out in 203 subjects including 60 controls. A modified technic for assaying B-glucuronidase activity was used that employs glass column chromatography and Sephadex. Although the lowest mean value was in the group of patients with cancer of the pancreas, there was wide range of activity of B-glucuronidase in all groups and subgroups and considerable overlap in values between them. It was concluded, therefore, that B-glucuronidase activity assay of the duodenal contents was of no value as a diagnostic test for cancer of the pancreas or for distinguishing between the several diseases affecting the pancreas.