Nosocomial diarrhea may be the second or third most common nosocomial infection, depending on the type of institution and the presence of outbreaks. Age is a major determinant of the type of cause of the diarrhea and, as a consequence, the choice of treatment. Control of nosocomial outbreaks is usually linked to prompt diagnosis and treatment of individual cases, interruption of the route(s) of transmission, and an increase in the awareness of infection-control procedures. Unfortunately, the complete elimination of nosocomial diarrhea is not feasible, and these infections will remain a challenge to us all in the future.