Twenty-nine infants (2-4 months old), with pathological gastroesophageal reflux assessed by 24-h esophageal pH monitoring, were studied. Cisapride or placebo was randomly added to positional treatment, prone-antiTrendelenburg position, which was applied to all infants. The pH monitoring was repeated after 13-16 days of treatment and revealed a significant improvement in both groups for most parameters. But the number of reflux episodes lasting longer than 5 min and the total number of reflux episodes had not decreased significantly in the placebo group. Only in the number of reflux episodes lasting longer than 5 min was improvement during treatment significantly greater in the cisapride group. This suggests cisapride both prevented reflux and improved esophageal clearance. These results suggest that in addition to other therapeutic measurements, such as positional treatment (which was previously demonstrated to be effective in this age group), cisapride might be of benefit in the treatment of gastroesophageal reflux disease.