Summary This NIV audit was conducted across the North Central London network area, for a 3-month period in 2003. Five trusts participated (on 6 hospital sites) and 141 audit forms were returned, allowing data analysis for individual hospitals and for comparisons between hospitals. The results are discussed in line with the British Thoracic Society guidelines on NIV [British Thoracic Society Guideline. Non-invasive ventilation in acute respiratory failure. Thorax 2002;57:192–211] and the Modernisation Agency document [Critical Care Programme. Weaning and Long Term Ventilation. NHS Modernisation Agency; 2002]. Key areas for future work have been identified to facilitate service improvement.