In a group of 19 infants being evaluated for gastro-esophageal reflux, we investigated the effects of various carbohydrate solutions (glucose polymers, 5% dextrose in water, and 10% dextrose in water) on the rate of postcibal gastroesophageal reflux during the first 2 h after a test feeding. The high-osmolality feeding (10% dextrose in water) produced significantly more postcibal gastroesophageal reflux over the entire 2-h interval. The major difference occurred in the second postcibal hour when the amount of gastroesophageal reflux was persistently high for 10% dextrose in water in contrast to the other feedings. We speculate that more rapid gastric emptying of low-osmolality solutions may account for these differences. Clear liquid feeding composition should be standardized during pH testing. Low-osmolality glucose polymer solutions may be more easily tolerated by infants with gastro-esophageal reflux who require carbohydrate or fluid supplements.