Children suffering from mild to moderate (3 to 6%) dehydration likely caused by viral gastroenteritis are often hospitalized because they are unable to tolerate oral fluids. We studied 17 such children, aged one to six years, who were otherwise healthy. All had isonatremic dehydration and were treated with 30 ml/kg of 3.3% dextrose and 0.3% saline over a period of three hours in the emergency department before being discharged. No patient required admission to the hospital. Only one patient required another course of rapid intravenous rehydration and subsequently improved without hospitalization. Although all our patients experienced vomiting before treatment, 65% had no vomiting after treatment. Rapid intravenous rehydration is an effective treatment, for children with mild to moderate dehydration secondary to presumed viral gastroenteritis, that obviates the need for hospitalization.