The countries surrounding the Persian Gulf are remarkable for the variety of infectious and contagious diseases that will affect those deployed to this area. In addition to the common gastrointestinal problems often seen in deployed troops, they will be exposed to such unusual problems as malaria, schistosomiasis, leishmaniasis, and rabies. Medical personnel will need to consider diseases that they have never before treated or diagnosed, and will have to educate their troops regarding control of vectors, avoidance of exposure, and personal hygiene and sanitation. Proper predeployment vaccination, use of appropriate prophylaxis, and use of countermeasures such as insect repellent will keep the spread of disease minimal.