The maturation value (MV), cervical mucus parameters (ferning, Spinnbarkeit), oestrone (E1), oestradiol (E2), oestriol (E3), follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), thyrotropin (TSH), growth hormone (GH), sex hormone binding globulin (SHBG), corticosteroid binding globulin (CBG) and thyroxin-binding globulin (TBG) were determined in 11 post-menopausal women presenting with vaginal atrophy prior to, and following, treatment with Ovestin vaginal cream containing 0.5 mg/day of E3 for 8 wk. In 6 of the patients E3 was measured during frequent plasma sampling on days 1, 21 and 56; in the same patients and on the same days TRH-stimulated PRL, TSH and GH levels were estimated. While the therapy induced a sharp rise in the MV, there was a moderate effect on ferning/Spinnbarkeit. Baseline E3 rose from undetectable levels to a mean value of 86.8 pmol/l at day 21. E3 levels achieved during frequent plasma sampling were higher on day 1 than on days 21 and 56 - a decline of the areas under the response curves being significant (P2-sided = 0.03). There was a slight suppression of FSH and LH. No changes in the circulating levels of E1, E2, SHBG, CBG, TBG, PRL, TSH and GH were seen. TRH-stimulated PRL, TSH and GH levels remained unaffected. Clinical effect was excellent and no untoward effects were reported.