Traveler's diarrhea is the most common health problem in persons who visit developing countries. Dietary precautions are the mainstay of prevention. Since bacteria are responsible for 50 to 80 percent of cases of traveler's diarrhea, antibiotics are the drugs of choice for empiric therapy. Because bacteria are becoming increasingly resistant to trimethoprim-sulfamethoxazole and doxycycline, newer antibiotics, especially the fluoroquinolones, should be considered as first-line therapy. Antimotility agents may help reduce symptoms, but they should not be given to patients who have fever or bloody diarrhea. Antibiotic prophylaxis is recommended for certain high-risk individuals.