SummarySome dynamic tests which may he used by clinicians are studied. Hypo-thalamo-pituitary-somatotrophic axis can be stimulated by insulin hypoglycemia, pyrogens,ß-methylcholine and total neurohypophyseal extracts; it is inhibited hy hyperglycemia.FSH blood level is reduced by oestrogen therapy while it is increased after the injection of neurohypophyseal extracts or synthetic oxytocin in young male. Testosterone is without effect on FSH in men while estrogens decreases FSH levels. The LH secretion is lowered alter oestrogen or testosterone injection and is increased, following injection of neurohypophyseal extracts in young male.