An analysis of the optimal conditions of ethanol, alkali, and DHIA concentrations, and of time and temperature for the Zimmermann reaction have been presented, as well as two procedures for the hydrolysis, extraction, and determination of 17-ketosteroids in crude urine extracts. A new modification of the Zimmermann reaction, using alkali in 80% ethanol, has been presented, showing the advantages and disadvantages over the Callow and Holthorff-Koch procedures.