Electrocortin was 25 to 30 times as active as DCA since only 1.5 to 2.0 [mu]g/kg/day were required for the maintenance of life in an adrenalectomized dog. The effect of Electrocortin was not identical with DCA. For example, overdosage of Electrocortin did not produce any marked retention of water, sodium or chloride. If insufficient Electrocortin was given, the non-protein nitrogen value increased considerably, whereas the hemoglobin concn. was only slightly increased; also, the concn. of chloride and sodium in plasma dropped after a few days. On changing from DCA to an adequate dose of Electrocortin, the water, sodium and chloride excretions in the urine increased. The concn. of chloride, sodium and potassium in plasma showed no clearcut changes. In water load expts. the Electrocortin acted in the same manner as DCA.