As travel by air increases, so does the number of passengers with chronic or acute medical issues. To evaluate fitness for air travel, it is necessary to consider the impact of the altered atmospheric surroundings in an airplane on the current illness to avoid a worsening of health conditions or even an emergency. As first medical contact person, the general practitioner will define supportive measures together with the patient and discuss these with the Medical Service of the airline for implementation. After a thorough evaluation, most patients will be classified fit to fly. Furthermore, a pre-travel consultation should address necessary vaccinations and information on infectious diseases.