Plasma levels of oestrone and oestradiol-17beta were determined at 20 or 30 minute intervals for up to 24 hours in 26 postmenopausal or ovariectomised women of similar age, weight, and number of years since menopause or operation. Results in women with both superficial dyspareunia and flushes were compared with those in women with flushes only, and with those in symptomless women. Women with superficial dyspareunia had significantly lower mean concentrations of plasma-oestradiol, but not of oestrone, than symptomless women. Flushes were not related to plasma-oestrogen. The implications of these findings in relation to the optimum dose of oestrogen for treating climacteric symptoms are discussed.