Background: Noninvasive ventilation (NIV) is standard of care for chronic hypercapnic respiratory failure, but indications, devices, and ventilatory modes are in constant evolution. Research question: To describe changes in prevalence and indications for NIV over a 15-year period; to provide a comprehensive report of characteristics of the population treated (age, comorbidities, and anthropometric data), mode of implementation and follow-up, devices, modes and settings used, physiological data, compliance, and data from ventilator software. Study design and methods: Cross-sectional observational study designed to include all subjects under NIV followed by all structures involved in NIV in the Cantons of Geneva and Vaud (1,288,378 inhabitants). Results: A total of 489 patients under NIV were included. Prevalence increased 2.5-fold since 2000 reaching 38 per 100,000 inhabitants. Median age was 71 years, with 31% being > 75 years of age. Patients had been under NIV for a median of 39 months and had an average of 3 ± 1.8 comorbidities; 55% were obese. COPD (including overlap syndrome) was the most important patient group, followed by obesity hypoventilation syndrome (OHS) (26%). Daytime Paco2 was most often normalized. Adherence to treatment was satisfactory, with 8% only using their device < 3.5 h/d. Bilevel positive pressure ventilators in spontaneous/timed mode was the default mode (86%), with a low use of autotitrating modes. NIV was initiated electively in 50% of the population, in a hospital setting in 82%, and as outpatients in 15%. Interpretation: Use of NIV is increasing rapidly in this area, and the population treated is aging, comorbid, and frequently obese. COPD is presently the leading indication followed by OHS.