The aim of the study was to see if there are any correlations between changes in the endocrine system and clinical condition of asthmatic patients, in particular their lung function, caused by hormone replacement therapy (HRT). Fifty-five asthmatic and 20 healthy postmenopausal women (aged 48-60) were studied before HRT and after 6 months of cyclical transdermal 17 beta-estradiol and medroxyprogesterone acetate treatment. Serum estradiol, cortisol and dehydroepiandrosterone sulfate (DHEAS) concentrations were assessed with the use of RIA, and spirometry parameters were measured. Statistically significant diminution of asthma exacerbations, reduced consumption of inhaled glucocorticosteroids and improvement in all investigated spirometry parameters was shown in patients treated with glucocorticosteroids during HRT. A reduction in mean 24-hour serum estradiol levels in asthmatic women was noted, whereas cortisol and DHEAS serum concentrations were decreased in asthmatic patients treated with glucocorticosteroids compared with the control group, before HRT. HRT produced increases in the concentrations of estradiol, cortisol and DHEAS in serum. Significant positive correlations were noted between estradiol concentrations and small and medium bronchi tests. In conclusion, HRT in postmenopausal asthmatic women has a favorable influence on the course of asthma, reduces daily use of glucocorticosteroids and frequency of asthma exacerbations and normalizes serum concentrations of estradiol, cortisol and DHEAS, which were decreased before HRT.