Objective: To investigate the effects of estrogen and progesterone on steep in postmenopausal women. Method: The 33 participants were randomly assigned to an estrogen or placebo group after undergoing clinical and hormonal assessments and a polysomnogram, and they underwent the same tests again after 12 weeks. Then, white still taking estrogen or placebo, they all received progesterone for another 12 weeks and underwent a final polysomnogram. Results: Estrogen plus progesterone was more effective than estrogen alone in decreasing the prevalence of periodic limb movement (PLM) (8.1% vs 2.8%), hot flashes (14.2% vs 0%), and bruxism (11.1% vs 0%) at night, or somnolence and attention difficulty during the day. The prevalences of breathing irregularities, arousal from steep, anxiety, and memory impairment were decreased in both groups following progesterone treatment. Conclusion: While not significantly affecting steep quality, hormone therapy decreased the prevalence of arousal in both groups and that of PLM in the group treated with estrogen plus progesterone. (c) 2008 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.