The effect of cisapride, a new gastrokinetic drug, on gastroduodenal motility was tested in six healthy volunteers. In order to obtain a model for slowed gastric emptying, dopamine was infused at a rate of 8 micrograms/kg/min. Dopamine significantly slowed the fractional emptying rate of fasting gastric contents from 5.14 +/- 0.37 to 1.45 +/- 0.67 %/min. Injection of either 10 mg of cisapride or 10 mg of metoclopramide restored emptying rate to normal (5.87 +/- 0.56 and 5.62 +/- 0.61 %/min, respectively). When cisapride was given without dopamine background, emptying was only moderately enhanced. Reflux of bile salts was not significantly affected by either cisapride or dopamine alone. When given on a dopamine background, however, both metoclopramide and cisapride decreased bile salt reflux below control values without any active treatment. It is concluded that emptying of fasting gastric contents can be speeded by cisapride, particularly when emptying is slowed by dopamine. A clear effect on bile salt reflux cannot be demonstrated.