Many of our patients travel by air. During the flight, they are exposed to specific physical conditions: decrease of the PaO2, increase of body gas volume and decrease in humidity. Depending on their illness, their tolerance to these conditions may vary. The primary care physician's role is to adequately counsel patients in order to ensure their security during and after the flight, as well as to prescribe additional therapies, when needed. Patients with a hypoxemic medical condition or patients that were recently operated deserve particular attention. Complications of common ear, nose and throat diseases should not be underestimated. Preventive recommendations for thromboembolic disease need to be addressed, while drug prophylaxis is not systematically recommended any more for patients with major thromboembolic risk factors.