Abstract (1) D-amphetamine stimulates growth hormone (GH) secretion, probably through its catecholaminergic effects. (2) In normal post-menopausal women we found the GH response to dextroamphetamine to be small and significantly less than that seen in young normal men. (3) In post-menopausal women but not in young men, the GH response to amphetamine was significantly higher in the evening than in the morning. (4) The reduced GH responses to dextroamphetamine in postmenopausal women may be due to sex difference, hypoestrogenism, or to reduced brain catecholamines associated with age. (5) The diurnal variation of the GH response to d-amphetamine in post-menopausal women may reflect a diurnal variation in hypothalamic nor-adrenergic activity higher in the evening, which was not masked by a reciprocal variation in estradiol levels.