Childhood diarrhea accounts for a substantial number of primary care visits. Historically, pediatric diarrheal disease was a significant cause of morbidity and mortality in children. Treatment for acute gastroenteritis has changed greatly over the past century, from i.v. therapy to the current use of oral rehydration therapy (ORT). This article highlights the development of ORT, addresses recent ORT controversies, and provides an overview of the current practice guidelines offered by the American Academy of Pediatrics in March 1996 for the management of acute gastroenteritis in children ages 1 month to 5 years.