Context-Previous studies suggest that elevated levels of estrogen and progesterone, either through endogenous or exogenous sources, increase gastroesophageal reflux.Objective-To evaluate the relationship between symptoms of gastroesophageal reflux disease and postmenopausal hormone therapy, including the use of selective estrogen receptor modulators and over-the-counter hormone preparations.Design, setting, and participants-Prospective cohort study of 51,637 postmenopausal women enrolled in the Nurses' Health Study who provided data on the use of hormone therapy biennially since 1976, and information about symptoms of gastroesophageal reflux in 2002.Main outcome measure-Self-reported symptoms of heartburn or acid-regurgitation occurring at least once a week in the previous year (reflux symptoms).Results-Among eligible participants, 12,018 (23%) women reported reflux symptoms. Compared to women who never used postmenopausal hormones, the multivariate odds ratio (OR) for the risk of reflux symptoms was 1.46 (95% CI 1.36-1.56) for past hormone users, 1.66 (95% CI 1.54-1.79) for current users of estrogen only, and 1.41 (95% CI 1.29-1.54) for current users of combined estrogen and progesterone. The risk of reflux symptoms increased significantly with increasing estrogen dose (P < 0.001) and increasing duration of estrogen use (P < 0.001). Moreover, current selective estrogen receptor modulator users experienced an OR of 1.39 (95% CI 1.22-1.59) for reflux symptoms, and women currently using over-the-counter hormone preparations had an OR of 1.37 (95% CI 1.16-1.62). Conclusions-Postmenopausal use of estrogens, selective estrogen receptor modulators, or overthe-counter hormone preparations is associated with an increased risk of symptoms of gastroesophageal reflux. This suggests a hormonal component to the pathophysiology of gastroesophageal reflux in women.