Duodenogastric reflux has a deleterious effect on the gastric mucosa. It was the aim of this study to assess the acute effects of cisapride on antroduodenal motility and duodenogastric reflux in seven patients with severe dyspepsia and increased biliary reflux, as evidenced by increased bile salt output in their gastric aspirates. Each patient underwent two studies on separate days. On each day, after an overnight fast, each patient swallowed a multilumen tube for manometric recording of gastroduodenal motility. Phenol red was infused into the second portion of the duodenum, gastric juice was aspirated, and motor activity was monitored for 90 min. At the end of this period, the patient received either cisapride or placebo intravenously in a double-blind randomized fashion. Antroduodenal motility and duodenogastric reflux were monitored for the subsequent 90 min. A significantly (P less than 0.01) higher motility index was found in the antrum after cisapride (2678 +/- 712 vs 1110 +/- 412 in the basal period) while placebo had no effect. The duodenal motility index was not affected by cisapride or placebo. Bile salt outputs in gastric aspirates were significantly (P less than 0.05) reduced following cisapride injection (0.42 +/- 0.6 mmol vs 1.6 +/- 1.2 mmol during basal period). Conversely, outputs of phenol red in the gastric aspirates were unaffected by cisapride. In conclusion, cisapride stimulates antral motility and decreases biliary reflux in patients with dyspepsia and increased duodenogastric reflux.