More than 50 million people, half of whom are Europeans (and more than 8 million of whom are French), travel each year from developed countries to tropical countries. About half of them will develop an illness during their trip. The full range of these illnesses is poorly understood, overshadowed by the severity of malaria and the frequency of traveler’s diarrhea. Epidemiology has, however, assessed traveler-related illnesses in terms of morbidity and mortality. These studies, though few in number, are the focus of this literature review. They show that travel-related illness is not limited to infectious and tropical risks. They enable better-tailored prevention strategies by targeting at-risk groups, risky behaviors, or specific diseases, thereby raising hopes for a reduction in travel-related illnesses. These epidemiological studies form the foundation of travel medicine, a discipline whose goal is “to keep the traveler alive and in good health.” (R.A.)