Rotavirus and Norwalk agent cause most viral gastroenteritis in the pediatric population. Infection results in osmotic diarrhea, which can cause dehydration and acidosis. Oral rehydration therapy has been shown worldwide to be a safe and effective means of treating this disease. Formula feeding should be resumed as soon as possible; breast feeding should be maintained throughout the illness. Admission criteria are based on weight loss, serum sodium level and ability to rehydrate orally on an outpatient basis.