As a link in the series of studies on the functions of the diencephalo-pituituitary adrenocortical system in endogenous psychosis, an investigation was carried out on 26 cases of schizophrenia who received the standard bilateral lobotomy, for the purpose to find out how the frontal lobe affects to the endocrine functions and autnomic nervous systems. For this purpose ACTH (25 units) was administered intramuscularly to 17 cases of them, and the m echolyltest was conducted with the other 9 cases, measuring the lelvels of corticoids in serum and urine of both groups. For the controls, ACTH was administered to 9 cases of schizophrenia who did not receive lobotomy. The results of the study may briefly be summarized as follows. 1) In the control group after ACTH adiministration the serum 17-OHCS showed a tendency of a decrease in the cortical reserve capacity, and in the lobotomized group there could be seen an abnormal reaction to ACTH in addition to a decrease in the cortical reserve capacity. 2) Total blood cholesterol after the ACTH stimulation decreased temporarily, showing similar changes up to 30 minutes in both groups, but in the lobotomized group an increase in cholesterol could be observed thereafter, revealing a contrasting phenomenon to the decreasing tendency of the serum 17-OHCS. 3) The blood potassium decreased transiently 10 minutes after the ACTH administration in both groups and such changes were unstable in the control group while the blood potassium in the lobotomized group increased steadily. As for the fluctuations of urine potassium its excretion was decreased transiently after the ACTH administration in both groups, which later rebounded, and this recovery tendency was more marked in the lobotomized group. 4) 17-KS excreted in urine on ACTH stimulation increased accompanying a marked increase in the amount of urine in the case of lobotomized group. 5) The results of the mecholyl test revealed that even the lobotomized patients respond to mecholyl, but there can be observed a decline and delay in the reactivity. 6) Observations on the fluctuations of serum 17-OHCS, urine 17-OHCS and 17-KS conducted simultaneouly with the mecholyl test revealed a declinining tendency in serum free 17-OHCS while total 17-OHCS in urine to be rather increased in the lobotomized group. The quantity of 17-KS excreted in urine decreased at first and then increased, and such a tendency did not parallel with the change in the total 17-OHCS excreted in urine. In the patients showing identically the same pathological conditions there could be recognized no distinct correlation between the type of response to mecholyl and the corticoid picture. 7) While we can recognize a certain correlation between defect symptoms of the frontal lobe and the endocrine functions, when we investigate individual caes, we find complex features in the endocrine function and autonomic nervous system according to the constitution before the lobotomy and the postoperative pathological picture. Namely, in those patients in a quiet mentbal state, though they are not completely cured, both functions maintain the balance in the state of lowered tension. On the other hand, in those who show a premonition of unrest and excitation, both functions have become unstable. Moreover, those who may have hallucination and delusion and are in the state of chronic defect, so long as there occurs no excitation, they show the levels of function close to the normal. 8) Summarizing these findings, it may be said that there is a decreasing tendency of the response to the ACTH stimulation in the functions of the diencephalo-pituitary-adrenocortical system of chronic shizophrenic group, and distribution of the estimated values is larger than that of normal persons, and this tendency is still more pronounced in the lobotomized group. Furthermore, the dissection of the frontal lobe brings about a defective equilibrium in the reaction mechanism of regulating center in endocrine system, but once placed under a strong stimulus, this balance is broken and there occurs a marked disruption in the endocrine rhythm.