The aim of this study was to determine whether patients (n = 40) with chronic obstructive pulmonary disease (COPD) currently receiving short-burst oxygen therapy meet existing criteria for ambulatory oxygen. A prospective randomised balanced double-blind crossover design was used. Criterion (i) for ambulatory oxygen (desaturation by 4% to below 90% on the practice walk) was met in 21 patients; 15 of these 21 patients also met criterion (ii) (10% improvement in distance and/or breathlessness score with oxygen). Despite no evidence of desaturation in 19/40 patients, 9/19 improved their distance and/or breathlessness score with oxygen. This study has shown that many patients on short-burst oxygen meet existing criteria for ambulatory oxygen and may have been receiving suboptimal therapy. It supports recent proposals for the development of comprehensive assessment services which incorporate assessment for all categories of oxygen.