['A high prevalence of nocturnal hypoxia is noted in patients with chronic heart failure (CHF). Nocturnal hypoxia can be reversed by nasal oxygen or non-invasive assisted ventilation. However, controversy exists over the use of oxygen in CHF. We studied the effects of nocturnal nasal oxygen in CHF to demonstrate its effects on 6-min walk test, quality of life (QOL), NTproBNP, and echocardiographic parameters.', 'Ten patients aged 70+/-9 years received domiciliary oxygen (4 l/min) for one month. Oxygen was administered for a minimum of 8h every night via nasal prongs.', 'A 17% improvement was seen in the 6-min walk test, 298+/-98 m to 351+/-100 m (p=0.005) and a 27% improvement in the QOL, which improved from 26+/-12 to 19+/-7 (p=0.017). Acquired echocardiographic measures including ejection fraction, pulmonary pressure and diastolic parameters did not change.'] Does domiciliary oxygen therapy improve sub-maximal exercise capacity and quality of life in chronic heart failure?