The behavior of the secretion of ACTH, GH, and plasma cortisol during the insulin-induced hypoglycemia test on normal and obese children was studied. The secretion of the above-mentioned hormones was determined by calculating the integrals of the curves. The mean values of the integrals of the plasma cortisol and ACTH curves do not show any significant differences between the two groups of children. The mean values of the ratios between the integrals of the plasma cortisol and ACTH curves show a significant difference between the two groups (P smaller than 0.01). Since the mean values of the integrals of the plasma cortisol curves are practically the same in both groups, the difference in the above-mentioned ratios refers to the lower values of the integrals of the ACTH curves found in the obese children. This enables us to make the hypothesis that in the obese child the function of the pituitary-adrenal axis, at least during the insulin test, does not differ from the norm thanks to the adaptation of the ACTH secretion to the greater sensitivity of the adrenal glands to this hormone. In both the groups examined there was no correlation between the secretion of ACTH and plasma cortisol, between ACTH and GH, and between plasma cortisol and GH.