Various available forms of therapy can decrease morbidity and mortality associated with acute diarrhea. Oral fluids represent the cornerstone of therapy of all cases. A variety of agents acting nonspecifically can decrease diarrhea and improve other worrisome symptoms associated with enteric infection. Kaopectate makes the stool more formed but has little additional effects. Bismuth subsalicylate, an antisecretory agent, reduces the number of stools passed by about 50 percent and improves other associated symptomatology. The drugs that affect motility such as loperamide and diphenoxylate are the most active of the nonspecifically acting drugs. They must be avoided in patients with significant fever and dysentery. Trimethoprim/sulfamethoxazole is now considered the drug of choice for shigellosis due to the presence of ampicillin-resistant Shigella strains in most regions of the world. Trimethoprim/sulfamethoxazole is also an effective form of therapy for enterotoxigenic Escherichia coli infection and for traveler's diarrhea without definable cause. Erythromycin, although not proved to be effective against Campylobacter, probably shortens the disease. Furazolidone, although not dramatically effective, has a spectrum of activity that includes Shigella, enterotoxigenic E. coli, Campylobacter, and Giardia lamblia. It may not be effective in severely ill (hospitalized) patients with diarrhea. The various forms of available therapy can be administered empirically, depending on symptomatology. Mildly ill patients (one to three unformed stools in 24 hours with minimal additional symptoms) probably are best treated with fluids only. Mild to moderately ill persons (three to six unformed stools in 24 hours) can be treated with a drug that acts nonspecifically, such as bismuth subsalicylate or loperamide. Those with severe diseases (six or more unformed stools with moderate to severe associated symptoms), particularly when associated with fever and the passage of bloody mucoid stools, may be given an antimicrobial agent. The antimicrobial drug given will be determined by ancillary laboratory tests (dark-field examination or examination of a wet-mount preparation for motile Campylobacter or stool culture for Shigella, Campylobacter, or Salmonella) or may be administered on an empiric basis. Traveler's diarrhea can be eliminated in selected persons by the administration of a pharmacologic agent. Liquid bismuth subsalicylate is effective in large doses, which may be impractical. Studies with the tablet formulation suggest that it is partially effective in preventing the illness. Doxycycline and trimethoprim/sulfamethoxazole are more effective, particularly when admini