37 children under the age of 5 years hospitalized for acute diarrhoea and dehydration were randomized to receive oral or intravenous rehydration during 6 to 12 hours. Rehydration was satisfactory in both groups, with correction of dehydration, metabolic acidosis and sodium deficit at equal rates. The reintroduction of normal feedings was successful in most of the orally rehydrated children after 12 hours, but often unsuccessful in the i.v. therapy group. Consequently the orally rehydrated children showed a 2.9% weight gain by the time of discharge whereas the intravenously treated children did not gain weight in the hospital. The duration of diarrhoea was also shorter in the orally rehydrated children. Thus oral rehydration therapy was equal or superior to even rapid intravenous rehydration therapy in the management of acute diarrhoea in children.