A method for the differential quantitation of urinary beta-glucuronidases of human and bacterial origins is presented. The activity of human enzyme at pH 6.5 was 36 per cent of its peak activity at pH 5.0 while the activity of bacterial enzyme at pH 5.0 was 20 per cent of its peak activity at pH 6.5. By simultaneous determination of the activity in a mixture of the enzymes of these two sources at both pH 5.0 and 6.5 and by simple mathematic proportion the individual activity of human and bacterial enzymes could be determined separately. This provides a quick method for differential diagnosis between bacterial and non-bacterial disease of the urinary system.