While non-invasive positive pressure ventilation (NIPPV) has become an accepted management approach for patients with acute hypercapnia, it remains unclear whether it can also be beneficial in stable chronic obstructive pulmonary disease (COPD) patients with chronic respiratory failure. Randomised controlled trials (RCT) with a maximum duration of 3 months showed contradictory effects in blood gasses, dyspnoea, sleep efficiency and health-related quality of life. On the other hand, several uncontrolled trials did show positive results in patients with hypercapnia. Recently, an RCT compared the combination of NIPPV and long-term oxygen treatment (LTOT) with LTOT alone for a period of 2 years in hypercapnic patients. After this period dyspnoea decreased and health-related quality of life improved in the NIPPV compared to the LTOT group. Reasons for the contradictory results in the different trials are probably patient selection, adequacy of ventilation, and length of ventilation. Therefore, at this moment there is no conclusive evidence that NIPPV should be provided routinely to stable patients with COPD. However, a selected group of patients might have clinical benefits from it. Patients who are clearly hypercapnic, who can tolerate an effective level of ventilatory support, and who get enough time to adjust to the ventilator might show clinical benefits even after 3 months. A trial with ventilatory support in this group of patients can be considered.