Introduction. Obstructive sleep apnea (OSA), particularly intermittent nocturnal hypoxemia, is associated with erectile dysfunction (ED). Aim. We investigated in patients with OSA whether continuous positive airway pressure (CPAP) therapy has a long-term effect on sexual function, including ED, in the presence of other risk factors for ED. Methods. Within a long-term observational design, we reassessed 401 male patients who had been referred for polysomnography, with respect to erectile and overall sexual function. Mean +/- standard deviation follow-up time was 36.5 +/- 3.7 months. Patients with moderate to severe ED were stratified according to the regular use of CPAP. Main Outcome Measure. Changes of sexual function were assessed by the 15-item International Index of Erectile Function (IIEF-15) questionnaire, including the domains erectile function (EF), intercourse satisfaction, orgasmic function (OF), sexual desire (SD), and overall satisfaction (OS). Results. Of the 401 patients, 91 returned a valid IIEF-15 questionnaire at follow-up. Their baseline characteristics were not different from those of the total study group. OSA (apneahypopnea index >5/hour) had been diagnosed in 91.2% of patients. In patients with moderate to severe ED (EF domain <17), CPAP users (N = 21) experienced an improvement in overall sexual function (IIEF-15 summary score; P = 0.014) compared with CPAP non-users (N = 18), as well as in the subdomains OF (P = 0.012), SD (P = 0.007), and OS (P = 0.033). Similar results were obtained in patients with poor overall sexual dysfunction (IIEF-15 summary score <44). In patients with moderate to severe ED and low mean nocturnal oxygen saturation (=93%, median), also the EF subdomain improved in CPAP users vs. non-users (P = 0.047). Conclusions. These data indicate that long-term CPAP treatment of OSA and the related intermittent hypoxia can improve or preserve sexual function in men with OSA and moderate to severe erectile or sexual dysfunction, suggesting a certain reversibility of OSA-induced sexual dysfunctions. Budweiser S, Luigart R, Jorres RA, Kollert F, Kleemann Y, Wieland WF, Pfeifer M, and Arzt M. Long-term changes of sexual function in men with obstructive sleep apnea after initiation of continuous positive airway pressure. J Sex Med 2013;10:524-531.