1) In the cases who received electroshock treatment, a rapid increase in the citric acid concentration of blood has been recognized, showing on the average an increase of 30 to 40 per cent, with the maximum of 80 per cent. However, the value returns to the pretreatment level after one and a half hours to two hours, but no marked change in the citric acid concentration can be recognized in urine. 2) In the cases given insulin shocks, the citric acid concentration in blood during coma shows a decrease of 20 per cent and shows an increase on regaining consciousness, in the great majority; but there are some cases which do not show the decrease during coma. In the course of insulin treatment the value immediately before the next injection is lower than the normal value. 3) Subcutaneous injection of epinephrine increases the citric acid concentration. However among the schizophrenic and the depressive patients there are some who do not show an increase. 4) Successive adminstration of chlorpromazine decreases the citric acid concentration of blood. When glucose is given to the patients receiving the successive chlorpromazine administration, these patients show responses similar to the abnormal responses observable in the chronic schizophrenic and diabetic patients. 5) Oral adminstration of barbital shows the minimum value of the citric acid concentration in blood two to four hours after the administration.