• Sixty well-nourished, well-hydrated infants, 3 to 24 months of age with uncomplicated acute gastroenteritis, were enrolled in a prospective, randomized, double-blind study that compared the safety and efficacy of two oral solutions. The solutions differed primarily in the sodium concentration (60 v 30 mEq/L) and glucose concentration (2% v 5%). The mean serum sodium concentrations of the two groups did not differ significantly from each other at entry or at the end of the study period. In addition, there were no significant changes in the mean serum sodium concentration within each group at the end of the study period. No child in either group became hypernatremic. Our results indicate that a solution with a high concentration of sodium initially designed for the rehydration of dehydrated children also can be safely and effectively used as a maintenance solution for the treatment of well-hydrated children older than 3 months of age with acute gastroenteritis.