The gold standard for diagnosis of obstructive sleep apnea (OSA) is polysomnography. Recent studies have shown that reproductive-age women with polycystic ovary syndrome (PCOS) are at high risk for OSA compared with women without this condition. Obesity is one of the most significant risk factors associated with OSA in non-PCOS populations. The aim of this prospective study was to evaluate the risk for OSA among nonobese and obese women with and without PCOS. The study was conducted at an academic tertiary care medical center. Participants were 78 women 18 to 40 years old (44 with PCOS and 34 non-PCOS controls). All 78 subjects completed the Berlin questionnaire, a validated survey for assessment of OSA risk. The primary study outcome was fasting blood determination of androgens, glucose, and insulin. Women with PCOS were more obese than control women were body mass index (BMI), 35.1 (11.4) versus 28.8 (11.5) kg/m(2); P = 0.02). However, no differences in BMI were found after subjects were divided into nonobese (PCOS, n = 17; control, n = 26) and obese (PCOS, n = 27; control, n = 8) groups. There was a significantly higher prevalence of high-risk OSA in women with PCOS on the Berlin questionnaire compared with control women (47% vs 15%, P < 0.01). None of the nonobese women with PCOS or the nonobese control women screened positively for high-risk OSA on the Berlin questionnaire. The risk for OSA was similar among obese women with and without PCOS (77% vs 63%, P = 0.65). These findings indicate that the risk for OSA is high among reproductive-age women with PCOS. The increased risk is present only among obese women with PCOS. Although nonobese women with PCOS do not seem to be at an increased risk for OSA, polysomnographic studies are needed to confirm the presence of OSA.