Although the effects of hormone replacement therapy (HRT) used after the menopause on the cardiovascular system, bone tissue, mammary gland, endometrium, menopausal symptoms and sexuality has been well known, there are very few studies about the effects of HRT on the pulmonary functions. In this study, we evaluated the effects of HRT on the pulmonary functions. For this purpose the postmenopausal women were randomized into two groups, 0.625 mg conjugated equine estrogens + 5 mg medroxyprogesterone acetate as a HRT was given to the group I (n= 32), and placebo was given to the control group. Pulmonary function tests (PFT) were performed to the all cases by same technician before and three months after the treatment. FVC, FEV1, FEV1/FVC, FEF25-75 and PEF parameters of the groups were compared. There were no statistically significant differences between the two groups considering the age, duration of the menopause and body mass index (BMI) (p> 0.05). There were no statistically significant differences between the groups considering FVC, FEV1, FEV1/FVC and FEF25-75 values of initial and the 3rd months measurements (p> 0.05). But PEF levels of the HRT group were significantly different than the initial values three months after the treatment (4.42 +/- 2.6 and 4.84 +/- 1.1) (p= 0.023). There were no statistically significant differences between the other compared parameters of PFT. As a result among the PFT parameters of the postmenopausal women taking HRT, PEF that was used as on obstruction parameter was found elevated. So, we concluded that more detailed and prospective studies were needed about the effects of HRT on PFT.