Almost all the information about the effect of continuous positive airway pressure (CPAP) in patients with obstructive sleep apnoea (OSA) comes from clinical trials involving only middle-aged patients. The objective of this study was to assess the effect of CPAP treatment in elderly patients with severe OSA on clinical, quality-of-life and neurocognitive spheres.We performed an open-label, randomised, multicentre clinical trial in a consecutive clinical cohort of 224 elderly (⩾70 years old) patients with confirmed severe OSA (apnoea-hypopnea index ⩾30) randomised to receive CPAP (n=115) or no CPAP (n=109) for 3 months. A sleep study was performed by either full polysomnography or respiratory polygraphy. CPAP titration was performed by an autoCPAP device. The primary endpoint was quality of life (Quebec Sleep Questionnaire) and secondary endpoints included sleeprelated symptoms, presence of anxiety/depression, office-based blood pressure and some neurocognitive tests.The mean±SD age was 75.5±3.9 years. The CPAP group achieved a greater improvement in all qualityof-life domains ( p<0.001; effect size: 0.41-0.98), sleep-related symptoms ( p<0.001; effect size 0.31-0.91) as well as anxiety ( p=0.016; effect size 0.51) and depression ( p<0.001; effect size: 0.28) indexes and some neurocognitive tests (digit symbol test ( p=0.047; effect size: 0.20) and Trail Making Test A ( p=0.029; effect size: 0.44)) in an intention-to-treat analysis.In conclusion, CPAP treatment resulted in an improvement in quality of life, sleep-related symptoms, anxiety and depression indexes and some neurocognitive aspects in elderly people with severe OSA. @ERSpublications CPAP is effective in elderly patients with severe OSA in clinical and neurocognitive terms improving quality of life