ObjectivesObstructive sleep apnea (OSA) is among the least studied risk factors for erectile dysfunction (ED). We aimed to determine ED prevalence in newly-diagnosed OSA patients, describe their main characteristics and assess continuous positive airway pressure (CPAP) effects on ED.MethodsCross-sectional study assessing ED prevalence in OSA patients and open-label, parallel, prospective randomized controlled trial evaluating 3-month CPAP treatment effects on sexual function, satisfaction, and psychological, hormonal and biochemical profiles. Male patients newly diagnosed with moderate/severe OSA (apnea-hypopnea index >20 events·h−1), aged 18–70 years, attending the sleep unit of a Spanish hospital during 2013–2016 were considered. A total of 150 patients were recruited (75 randomized ED patients). ED was defined as scores <25 on International Index Erectile Function 15 test. Wilcoxon’s matched-pairs signed-ranks and rank-sum tests were used.ResultsED prevalence was 51%. Patients with ED were older (p<0.001), had greater waist-to-hip ratios (p<0.001), were more frequently undergoing pharmacological treatment (p<0.001) and had higher glucose levels (p = 0.024) than non-ED patients. Although significant increases in erectile function (mean(SD) change: +4.6(7.9); p = 0.002), overall satisfaction (+1(2.2); p = 0.035), and sexual satisfaction (+2.1(4.3); p = 0.003) were found after CPAP treatment, only differences in sexual satisfaction (p = 0.027) and erectile function (p = 0.060) were found between study arms. CPAP treatment did not impact psychological, hormonal or biochemical profiles.ConclusionsThis study confirmed the relationship between OSA and ED, suggesting the potential usefulness of ED screening in OSA patients, but could not determine conclusively whether CPAP is an effective stand-alone ED treatment, regardless of positive results on sexual satisfaction.Trial registrationClinicalTrials.gov NCT03086122