Only severe hypoxemia at rest in COPD patients has strong recommendations for long-term oxygen therapy. It is accepted that oxygen should be prescribed if PaO2 is ≤ 7,3 kPa (55 mmHg), or if PaO2 is ≤ 8 kPa (60 mmHg) in the presence of signs of pulmonary hypertension or a hematocrit ≥ 55 %. In Switzerland, prescription is governed by the LiMA (Liste des moyens et appareils) and the patient can obtain supplies from a health care provider or directly from the provider. The most suitable device taking patient's oxygen needs and mobility into account must be chosen. O2 prescription entails risks for the patient that must be known to the prescriber. This article presents the different aspects of long-term home oxygen therapy.