Obstructive and central sleep apneas are treatable disorders, which contribute to cardiovascular morbidity in older adults. Younger adults with Marfan syndrome may also be at risk for sleep apnea, but the relation between cardiovascular complications and sleep apnea is unknown. We used MiniScreen8 portable monitoring devices for polygraphy in 68 consecutive adults with Marfan syndrome (33 men, 35 women, 41 +/- 14 years old) to investigate frequency of sleep apnea and its relation to cardiovascular morbidity. The apnea-hypopnea index (AHI) was 6 to 15/hour in 14 subjects (mild sleep apnea, 21%), and AHI was >15/hour in 7 subjects (moderate or severe sleep apnea, 10%). Among established risk factors for sleep apnea, only older age (Spearman rho = 0.35, p = 0.004) and body mass index (rho = 0.26, p = 0.03) were associated with increased AHI. Of all cases of apnea, 12 +/- 27 were obstructive, 11 +/- 25 central, and 3 +/- 9 mixed. AHI was associated with decreased left ventricular ejection fraction (rho = -0.33, p = 0.01), increased N-terminal pro-brain natriuretic peptide levels (rho = 0.35, p = 0.004), enlarged descending aortic diameters (rho = 0.44, p = 0.001), atrial fibrillation (phi = 0.43, p = 0.002), and mitral valve surgery (phi = 0.34, p = 0.02). Of these, left ventricular ejection fraction, N-terminal pro-brain natriuretic peptide levels, atrial fibrillation, and mitral valve surgery were associated with AHI independently of age and body mass index. We found similar associations with oxygen desaturation index. In conclusion, sleep apnea exhibits increased frequency in Marfan syndrome and is not predicted by classic risk factors. Obstructive and central sleep apneas may relate to cardiovascular disease variables.