The morphologic changes evoked in the adrenal glands of male and female hamsters by gonadectomy (15 weeks) and gonadal-hormone replacement (single s.c. injection of 5 mg/l00 g b.w. testosterone or 0.5 mg/l00 g b.w. estradiol, 2 weeks before the sacrifice) were investigated by morphometric techniques and correlated with the functional alterations of the hypothalamopituitary-adrenal axis. Our findings evidenced a stimulatory role of androgens and a moderate inhibitory one of estrogens on the growth and steroidogenic capacity of the adrenal glands in male and female hamsters, respectively. Moreover, they suggest that these adrenal effects of gonadal hormones are, at least partly, independent of alterations in the pituitary ACTH release.