Twenty children (age range 75 days-47 months) with reflux oesophagitis entered a random double blind trial in which they received either Cisapride (Janssen Pharmaceutical Ltd), a new prokinetic agent, or an identical placebo syrup. Diagnosis of gastro-oesophageal reflux was made by measurement of intraluminal oesophageal pH combined with manometry. Oesophagitis was assessed in all patients by histological examination of mucosal specimens taken during oesophagogastroduodenoscopy. Manometry, pH test, and endoscopy with biopsy examination were repeated at the end of the treatment period. Seventeen patients completed the trial, eight of whom were taking the drug and nine the placebo. Mean total clinical score and post-prandial reflux time (% of reflux) significantly improved in patients in the group given Cisapride but not in the group given placebo. Furthermore, there was a significant improvement of the histological oesophagitis score only in the children in the group given Cisapride, whereas placebo was ineffective. It is concluded that Cisapride is a useful agent both for the relief of symptoms of gastro-oesophageal reflux and for the healing of peptic oesophagitis in infancy.