Non-invasive ventilation (NIV) is a clinically proven, cost-effective intervention for acidotic exacerbations of COPD that is recommended by UK national guidelines. This study examines the extent to which these recommendations are being followed in the UK. Between August and October 2003 a national audit of COPD exacerbations was conducted by the Royal College of Physicians and the British Thoracic Society. 233 (94%) UK hospitals submitted data for 7,529 prospectively recruited acute COPD admissions, documenting process of care and outcomes from a retrospective case note audit. They also completed a resources and organisation of care proforma. Nineteen hospitals (8%) reported they did not offer NIV. There was no access to NIV in 92 (39%) intensive care units in 88 (36%), high-dependency units or on general wards of 85 (34%) hospitals. In 74 (30%) NIV was available on all 3 sites. A low pH (<7.35) was noted at some time during admission for 26% (1714/6544) of patients and NIV was administered to 31%. Patients receiving NIV were more often admitted under a respiratory physician, or seen at some stage by a respiratory specialist and had more severe disease (higher PaCO2 (median 9.8 v 7.8 kPa), lower oxygen tension (median 8.8 v 9.8 kPa), higher incidence of peripheral oedema (48% v 39%), of pneumonia (27% v 16%), higher in-hospital mortality (26% v 14%) and at 90 days (37% v 24%) and longer hospital stays (median 9 v 7 days) than those not receiving NIV. Hospitals with least usage of NIV had similar mortality rates to those using NIV more often. A comprehensive NIV service is not available in many hospitals admitting patients with acute respiratory failure secondary to COPD. Access to acute NIV is inadequate and does not conform with NICE and BTS guidelines. These observational audit data do not demonstrate benefits of NIV on survival when compared to conventional management, contrary to results from randomised trials. Reasons for this are unclear but unmeasured confounding factors and poor patient selection for NIV are likely explanations.