Almost 2 billion people travel aboard commercial airlines every year. Health-care providers and travellers need to be aware of the potential health risks associated with air travel. Environmental and physiological changes that occur during routine commercial flights lead to mild hypoxia and gas expansion, which can exacerbate chronic medical conditions or incite acute in-flight medical events. The association between venous thromboembolism and long-haul flights, cosmic-radiation exposure, jet lag, and cabin-air quality are growing health-care issues associated with air travel. In-flight medical events are increasingly frequent because a growing number of individuals with pre-existing medical conditions travel by air. Resources including basic and advanced medical kits, automated external defibrillators, and telemedical ground support are available onboard to assist flight crew and volunteering physicians in the management of in-flight medical emergencies.