Since 1947 hypertonic dehydration associated with diarrhea has been recognized to result in a much greater morbidity and mortality of infants than does isotonic dehydration.1,2 Particularly serious have been convulsions and other manifestations related to the central nervous system (CNS).3-5 Improper parenteral fluid therapy is thought to aggravate the disorder of the CNS. Various regimens have been proposed in attempts to avoid these complications; however, none of these regimens has been evaluated in a controlled study. A controlled study was planned which would help to evaluate the results of two therapeutic regimens of parenteral fluid administration. From previous observations on a clinical service, we concluded that such a study would have to include a fairly large number of cases, and that etiologic factors, severity of dehydration and of chemical derangement, the patient's age and previous development, as well as the therapy might affect the rate of recovery and