The possible influence of moderate amounts of acetylsalicyclic acid (ASA) on gastric emptying, duodeno-gastric reflux and small bowel propulsion was studied in rats with permanent gastric and duodenal tubes. The ASA-containing or the control solution was introduced intra-gastrically half an hour before the simultaneous administration of differently labeled radioactive test meals into the stomach and the duodenum. ASA was given as 7.5 or 15.0 mM solution in 100 mM hydrochloric acid or in 100 mM sodium chloride. After 15 minutes the gastrointestinal propulsion was examined. No effect of the ASA treatment was noted. No increase in duodeno-gastric reflux was found in the ASA-treated animals.