Obstructive Sleep Apnea (OSA) is considerably more common in men than women. Preliminary data suggest that androgens may play a role in the male predominance of apnea. Polycystic Ovary Syndrome (PCOS) is characterized by menstrual disturbances, androgen excess, and frequently obesity. These features suggest that women with PCOS may be at increased risk for OSA. To determine whether obese women with PCOS have an increased prevalence of sleep apnea compared with age and weight-matched reproductively normal women, we performed overnight polysomnography for determination of the apnea-hypopnea index (AHI) in 18 obese women with PCOS and age and weight-matched control women. Additional measurements included waist, hip, and neck circumferences, serum total testosterone, unbound testosterone, and DHEAS. Women with PCOS had a higher AHI than controls (22.5 +/- 6.0, vs. 6.7 +/- 1.0, P = 0.008). Women with PCOS were also more likely to suffer from symptomatic OSA syndrome (44.4% vs. 5.5%, P = 0.008). AHI correlated with waist-hip ratio (r = 0.51, P < 0.03), serum testosterone (r = 0.52, P < 0.03) and unbound testosterone (r = 0.50, P < 0.05) in women with PCOS. We conclude that obese women with PCOS are at increased risk of OSA when compared with matched reproductively normal women. Women with PCOS should be carefully questioned regarding symptoms of sleep apnea.