Travelers' diarrhea is an important health concern for travelers, with an attack rate of approximately 40%. Except in the elderly or young children, who may have severe cases, travelers' diarrhea is usually mild but can lead to significant discomfort and to chronic forms. Bacteria, especially enterotoxinogenic E. coli, are its principal causes. Unsafe solid food is, even more than water, its main vector. Quinolones and azithromycin are very effective but rehydration remains the cornerstone of treatment. Quinolones can be used for preventive treatment but only for travelers at high risk. Other means of prevention include food hygiene, although its effectiveness is limited. More useful than forbidding foods is counseling travelers to wash their hands and eat safe food (cooked, hot). Preventive nonabsorbed antiinfective agents and vaccination against enterotoxinogenic E. coli should be available relatively soon and will decrease the incidence of travelers' diarrhea.