Abstract: There is evidence indicating that the cholinergic system positively modulates HGH secretion. In the present study, we observed the effects of cholinergic enhancement by pyridostigmine （PD）, a cholinesterase inhibitor, on hGH release in both normal （n=13） and hGH deficient （n=10） adolescents. Responses of hGH to insulin hypoglycemia （Ins） were also observed. In normal subjects, PD-induced serum hGH peak levels were significantly higher than that induced by Ins （P＜0.01）. By contrast, the hGH level in the patients with pituitary dwarfism showed no increase by both" tests. The study indicates that PD test may be considered a useful dyanamic test in evaluating pituitary function of hGH secretion in children and adolescents.