OBJECTIVES: To examine prospectively the association between snoring and incidence of cardiovascular disease (CVD) in women. BACKGROUND: Whether snoring increases risk of CVD remains unclear; most previous studies have been small, not prospective and limited to men. METHODS: Seventy-one thousand seven hundred seventy-nine female nurses 40 through 65 years of age and without previously diagnosed CVD or cancer at baseline in 1986 were followed up for eight years. Frequency of snoring was assessed using mailed questionnaires at baseline. RESULTS: During eight years of follow-up, we documented 1,042 incident cases of major CVD events (644 coronary heart disease [CHD] and 398 stroke). Compared with nonsnorers, the age-adjusted relative risks (RRs) of CVD were 1.46 (95% confidence interval 1.23 to 1.74) for occasional snorers and 2.02 (1.62 to 2.53) for regular snorers. The age- adjusted RRs of CHD were 1.43 (1.15 to 1.77) for occasional snorers and 2.18 (1.65 to 2.87) for regular snorers. The age-adjusted RRs of stroke were 1.60 (1.21 to 2.12) and 1.88 (1.29 to 2.74), respectively. After further adjustment for smoking, body mass index (BMI) and other covariates, the positive association between snoring and CVD was attenuated but remained statistically significant (RRs of CVD were 1.20 [1.01 to 1.43] for occasional snorers and 1.33 [1.06-1.67] for regular snorers. CONCLUSIONS: These data suggested that snoring is associated with a modest but significantly increased risk of CVD in women, independent of age, smoking, BMI and other cardiovascular risk factors. While further study is needed to elucidate the biological mechanism underlying this association, snoring may help clinicians identify individuals at higher risk for CVD. (C) 2000 by the American College of Cardiology.