Summary1) The introduction of Allen’s correction into Reddy’s modified method obviously increases its value as shown by many experimental data.2) Through the use of this correction it is shown that many of Reddy’s various procedures loose their interest. Only the modification which consists to carry the Porter and Silber reaction in a less acid medium (sulfuric acid20N) at room temperature during 12–18 hours, deserves to be introduced into the method of dosage. This modification has indeed the advantage of practically equalizing the optical densities of the four main urinary corticoids depicted by the Porter and Silber reaction.3) Comparison of the results yielded by the methods of Reddy and of Glenn and Nelson on one hand and that of Norymberski on the other, further stresses the advantage of Reddy’s modified procedure, owing particularly to its remarkable simplicity. In this laboratory one technician is able to carry out 18 determinations within half a day.