To investigate the corticoid metabolism In Vivo of endogenous psychosis, authors have studied the relationship between urinary and serum corticoid patterns. Twenty four hour urine and blood samples were taken from 17 cases of both sexes of schizophrenic patients, 17 cases from both sexes of depressed patients, 17 cases from both sexes of normal control persons, 11 cases of right and left lobotomized chronic schizophsenic patients and 12 cases from both sexes of patients with pituitary tumors, pituitary cysts, craniopharyngeomas, disturbances in hypothalamus and so on. The urinary 17-KS were measured by a modified method of Koch and Holtorff and 17-OHCS were measured by Silber-Porter and Bongiovanni. Bacterial β Glucuronidase was used in hydrolysis. The results were as follows: 1. Free 17-OHCS in the urine and the serum were increased in schizophrenic and depressed patients in aggravating situations without exception. 2. Urinary 17-KS were decreased in aggravating situations in both schizophrenic and depressed patients. 3. The decrease of urinary 17-KS was significant in the male but not in the female. 4. High serum 17-CHCS levels were followed by high urine 17-OHCS values; in other words the values moved parallel in psychotic patients. 5. The value of conjugated 17-OHCS over free 17-OHCS (C/F) in the urine and blood always decreased in schizophrenic and depressed patients. 6. The ratios of urinary 17-KS over free serum 17-OHCS, and urinary total 17-OHCS over free serum 17-OHCS showed significant relationships in both schizophrenic and depressed patients; these ratios are decreased in an aghravating situation. 7. The frontal lobe plays a role in urinary 17-KS excretion. It should be emphasized that separating the frontal lobe from the thalamus or hypothalamus area will cause an increase in urinary 17-KS excretion. 8. Urinary or serum 17-OHCS values du not move in parallel to urinary 17-KS but rather in a reverse manner in psychotic patients.