The major disorder of water and electrolyte metabolism in children is dehydrating diarrhea. The major advance in the treatment of this condition has been the development of oral rehydration therapy, ie, the enteral administration of a balanced glucose-electrolyte solution. This therapy is effective in patients of all ages, dehydration of all degrees short of hypovolemic shock, with gastroenteritis of all causes, and electrolyte disturbances including hypo- and hypernatremia. This review highlights current experimental and clinical studies that have focused on oral rehydration solutions that have the additional benefit of reducing the severity and duration of diarrheal disease. Recent results have been conflicting, however, and the search for the optimal solution continues.