INTRODUCTION: Commercial airline travel poses a recognized risk to patients with respiratory disease, including in those with asthma. Hypoxic challenge testing (HCT) is typically employed to mitigate this risk by dictating in-flight oxygen requirement.METHODS: The role of HCT has not been formally studied in patients with severe asthma and we therefore evaluated HCT assessment in a cohort of patients with severe asthma (N = 37).RESULTS: Over half (57%) of patients had a positive HCT. Baseline oxygen saturation (S_po₂) was poorly predictive of a recommendation for supplementary oxygen in flight; two-thirds of those deemed to require oxygen had a baseline S_po₂ > 95%. A combination of any two of: P_ao₂ ≤ 10.5 kPa, FEV₁ ≤ 60% predicted, and PEF ≤ 350 L · min⁻¹ predicted the need for in-flight oxygen with a sensitivity of 89% and a specificity of 69%. Furthermore, no patient with an S_po₂ > 95% and FEV₁ > 85% predicted had a positive HCT.CONCLUSION: Overall, the findings indicate that HCT should be considered for all patients with severe asthma, regardless of resting oxygen saturation level.George PM, Orton C, Ward S, Menzies-Gow A, Hull JH. Hypoxic challenge testing for fitness to fly with severe asthma. Aerosp Med Hum Perform. 2016; 87(6):571–574.