Diarrheal diseases result from two different processes: toxin elaboration by pathogens such as Vibrio cholerae and some strains of Escherichia coli and invasion of tissue, eg, by shigellae and salmonellae. Intestinal motility serves as a normal cleansing mechanism of the intestine, and drugs that decrease this motility may facilitate replication of pathogens and their attachment to or invasion of the intestinal tissue. Therapy should not be aimed at suppressing the symptom of diarrhea. It is now known that the electrolytes lost in the course of diarrheal disease can be replaced orally if they are given in solution with glucose. Although commercial preparations are not readily available, an effective solution can be made from ingredients commonly found in the home. Oral rehydration has greatly simplified treatment and has significantly reduced the morbidity and mortality associated with diarrheal diseases.