Non-invasive ventilation (NIV) is recognized as first line therapy in acute hypercapnic respiratory failure and chronic alveolar hypoventilation caused by several diseases (restrictive thoracic disorders, neuromuscular disease and obesity-hypoventilation syndrome). In Switzerland and other European countries, long-term NIV has also been applied in hypercapnic patients with chronic obstructive pulmonary disease (COPD). However, only recently has conclusive evidence showing benefits of long-term NIV become available. Long-term NIV in COPD has now shown its efficacy in many studies. However, despite these findings, indications, ventilatory settings and monitoring remain poorly known and topic of debate.