In order to determine if cortisol (F) concentrations are as good as adrenocorticotropin (ACTH) concentrations, in evaluating hypothalamic-pituitary-adrenal axis function we measured ACTH and cortisol concentrations after the administration of L-DOPA and insulin in 9 boys, with short stature, mean age of 12.11 years. The means (X's) and standard deviations (SD's), over two hours period, for ACTH and cortisol, after L-DOPA are 43.5 /± 41.6, 18.76 /± 6.95, for growth hormone deficient group and 30.7 /± 27.2, 14.6 /± 6.34, for non-growth hormone deficient group. The X's and SD's for ACTH and cortisol, after insulin are 80.5 /± 49, 31.47 /± 7.47, for growth hormone deficient group and 71 /± 61, 23.87 / ± 6.65, for non-growth hormone deficient group. No significant statistical differences were detected in the ACTH and cortisol concentrations, between growth-hormone deficient and non-growth hormone deficient groups. There were significant differences (p<.02) in ACTH and cortisol responses, between L-DOPA and insulin stimuli, for all the comparisons. To assess the ACTH/F relationship over the four hours of the test, a multiple linear regression model yielded a correlation coefficient of r =.86, which explains 74.2% of the relationship between ACTH and cortisol. The concentration of ACTH, at any point in time, predicts cortisol values, thirty minutes later, better then concomitant cortisol values. Insulin hypoglycemia was shown to be a more powerful stimulus, compared to L-DOPA. The high correlation coefficient between ACTH and cortisol, suggests that cortisol levels represent an accurate assessment of the hypothalamic-pituitary-adrenal axis function, in children with short stature.