Prolonged cerebral electrostimulation of subconvulsive intensity has been employed as an experimental procedure at this hospital during the past year, and the indications for this technique in the treatment of mental disorders are being investigated. Preliminary tests in conjunction with Dr. H. Weil-Malherbe showed that electrostimulation, when applied to normoglycaemic patients under pentothal anaesthesia, caused a pronounced increase in the concentration of adrenaline-like substances in the blood during the passage of the current. The same current was therefore applied to a series of patients in hypoglycaemic coma to determine whether the effects obtained after injection of glutamic acid—and considered by Weil-Malherbe (1949) to be adrenergic in origin—could also be obtained after electrostimulation. The results of these investigations are presented in this report. The stimulating current employed for this purpose was of the “square wave” (interrupted galvanic) type, which was first applied as a cerebral stimulus by Leduc (1902) in his pioneer demonstration of electrical anaesthesia and sleep. More recently Liberson (1945) has investigated this type of current in relation to E.C.T., subsequently utilizing it in his Brief Stimulus Technique (Liberson, 1947, 1948). This latter technique is also under investigation here at the present time, the same stimulator being used for both convulsive and sub-convulsive therapies; the results obtained with the Brief Stimulus convulsive therapy will be presented in a later report.