To prevent diarrhea, efforts must be directed toward decreasing environmental contamination of enteropathogens, altering exposure of persons to naturally occurring agents, or to increasing host tolerance to prevalent enteropathogens. A vaccine is feasible in the control of certain enteric infections among high risk groups: typhoid fever and cholera, in areas of hyperendemicity or during an epidemic, shigellosis in institutionalized populations that are at risk to develop illness due to known prevalent serotypes, enterotoxigenic Escherichia coli for US travelers to Latin America, and perhaps rotavirus for all children under 3 years of age. In diarrhea, the most useful form of treatment is an oral glucose/electrolyte solution, which in most cases will prevent dehydration. Lactose containing foods should be removed from the diet early in the course of diarrhea. Antimicrobial agents are necessary in the treatment of typhoid fever, are useful in the treatment of shigellosis, giardiasis, and amebiasis, and are contraindicated in intestinal salmonellosis.