This paper gives a general overview of the telemedicine service on board airplanes, by considering the problems associated with it, the institutions that are already operating in the field, and the main projects (public and private) that are investigating in this direction. It also reports a brief discussion about the potential market and concludes with a number of issues related to such a service. Most of this information comes from the authors' active participation in several European projects that are particularly focused on telemedicine.