IT HAS BEEN FOUND (1) that the amount of andro gen excreted in the urine of normal adults varies from day to day when determined by the Zimmermann (2) reaction. This fluctuation is approximately ± 40% about a mean which is relatively constant for an individual, even over long periods of time. This finding has been recently confirmed (3). However, Callow (4) demonstrated that there is normally a nonspecific chromogenic fraction which gave a color value of about 6% of the total in a small number of urine specimens from several subjects. Talbot (5) confirmed this although he found a much higher value for this fraction in a number of instances. The question thus arises whether the daily fluctuation in total androgen output of the individual subject is accounted for by changes in the output of this nonspecific component or in the output of the specific 17-ketosteroids. Callow (4) has used the ratio of absorption coefficients with green and violet filters EG/EV, to determine whether an extract is relatively pur...