OBJECTIVE By 2008 it is projected that over two billion people will be travelling by commercial aircraft each year. With an ageing population and treatment improvements, many of these travellers will have lung disease, particularly chronic obstructive pulmonary disease. Current guidelines as to whether a patient requires supplemental oxygen during the flight are based on limited research evidence. Awareness of the increased risk has resulted in recent scientific interest in this area. RESULTS Studies have demonstrated a lack of consistency in international guideline recommendations when performing assessments within the respiratory laboratory. This has led to more specific analysis of patients, including in-flight assessments, the inclusion of exercise stress and more interest in actual cabin pressure conditions. CONCLUSIONS Commercial air travel is generally safe for patients with chronic obstructive pulmonary disease when their disease is stable. All current guidelines reflect the considerable uncertainty in relation to the clinical circumstances when oxygen prescription during flight is essential. Currently planned flight outcome studies will provide more precise risk quantification.