Concerning the adrenocortical hormones and the aging process, especially in childhood and adolescence, the results by age level of the studies by the author and coworkers on the following items are summarized : 1) Plasma levels of cortisol and corticosterone, 2) Plasma transcortin binding of C-14 cortisol (% bound) and erythrocyte C-14 cortisol uptake, 3) Plasma cortisol levels after ACTH stimulation and also the values in patients immediately after death, 4) Certain important urinary metabolites of cortisol, 5) Urinary excretion of tetrahydroaldosterone, 6) Urinary excretion of 17-KS fractions.The level of cortisol in the plasma was slightly low during the newborn period, however transcortin binding of C-14 cortisol (% bound) was also low in newborns and young infants and cortisol value in the plasma after ACTH stimulation or immediately after death increased more markedly, showing higher values in young infants than in older children. Urinary metabolites of cortisol also showed age-specifity more markedly after ACTH stimulation. Even in young infants, urinary aldosterone excretion was increased after Narestriction in most of the cases examined. The production of adrenal androgens increased sharply before puberty and a close relationship was observed between the urinary excretion of 11-deoxy 17-KS fractions and the growth spurt during the adolescence period.These results showed that the secretion and metabolic pathways of the adrenocortical hormones of the children are different from those of the adult and even in the children they are not the same during each period of childhood. We would like to emphasize that some of these differences due to age becomes more marked under conditions when the adrenal glands become stimulated.To study the alternation of functions of adrenal cortex and adrenal medulla and the relationship between them in aged persons, plasma levels of cortisol and corticosterone, urinary excretion of 17-ketogenic steroid fractions, pregnanediol (P-diol), pregnanetriol (P-triol), catecholamines (CA), total metanephrine (TMN) and VMA were measured by J.v.d. Vies', modified Morris', Klopper's, modified Stern-Few's, modified Eular-Lis-hajko's, Pisano's and Sandler's method respectively. Hormones and thier metabolites above mentioned in young and adult subjects also were measured as a control. Both groups of examined persons were healthy. The plasma levels of cortisol and corticosterone were within the range of the control. Daily urinary excretions of 17-ketogenic sterioid (17-KGS), 11-oxygenated 17-KGS (11-oxy 17-KGS), 11 -deoxy 17-KGS, P-triol and P-diol decreased in the aged but the ratio of 11-deoxy 17-KGS to 11-oxy 17-KGS elevated in over 8th decade. Following the intramuscular administration of ACTH-Z, the increase of 17-KGS, 11-oxy 17-KGS, P-diol and P-triol in the aged was less than in the control, but that of 11-deoxy 17-KGS was as much as that of the control. Therefore, the ratio of 11-deoxy 17-KGS to 11-oxy 17-KGS elevated in the aged. In the aged, the increase of 11-deoxy 17-KGS following the oral administration of SU-4885 was greater than that in the control, consequently showing a remarkable elevation of the ratio of 11-deoxy 17-KGS to 11-oxy 17-KGS. These results from both ACTH-Z test and SU-4885 test suggested that there was some disturbance of cortisol synthesis in adrenal cortex in the aged.In the aged, daily urinary excretions of noradrenaline (NA) and TMA increased more than in the control. The control showed significant difference as to sex, but the aged did not. Daily urinary excretion of adrenaline (A) in the aged showed large variation, but the mean value was within the range of the control. Urinary excretion of VMA in the aged was also within the range of the control. In the aged, the ratio of A to NA was lower, and that of TMN to VMA was higher than in the control, but that of CA to TMA was within the range of the control. In both aged and young subjects,