The present study aimed to evaluate gastric emptying in children with gastroesophageal reflux (GER) by means of real-time ultrasonography, on the basis of measurements of the cross-sectional area of the gastric antrum. Twelve children with GER were studied (seven males, five females; age range, 3-13 months) and compared with 12 normal control children (six males, six females; age range, 3-13 months). The diagnosis of GER was confirmed by 24-h esophageal pH-monitoring. The GER patients had a significantly greater antral area than the controls at 90, 105, and 120 min after eating a standard meal (cow's milk formula, 300 ml/m2 body surface area); in addition, final gastric emptying time was significantly greater in the patients than in the controls (145 +/- 36.9 versus 78.7 +/- 19.3 min; p less than 0.0025). After 8 weeks of treatment with cisapride (0.3 ml/kg, three times a day) 24-h esophageal pH-monitoring and ultrasonography studies were repeated in the patients. The total percentage reflux time was significantly lower (p less than 0.038), and ultrasonography showed a decreased antral area at all the various study times, with no significant difference between patients and controls; final gastric emptying time was also significantly lower than before treatment (p less than 0.009). Furthermore, in the GER patients there was a significant correlation between gastric emptying time and the sum of the various reflux times recorded in the 2 h after all meals over the 24 h.(ABSTRACT TRUNCATED AT 250 WORDS)