Various problems are encountered in measuring gastric emptying, especially relating counts to the volume of meal remaining in the stomach. We have developed a method which has been validated against aspiration of the stomach. In gastric ulcer patients, however, the stomach is large and overlaps the bowel. Results of gastric emptying studies in patients who have had surgery for peptic ulceration show that impaired gastric emptying is related to the extent of vagotomy and pyloric surgery. We have examined the pattern of biliary excretion of iminodiacetic acid derivatives and related enterogastric reflux to the amount of bile in the stomach as determined by aspiration. However the reproducibility is only 75% probably due to day to day variation in its occurrence. The incidence of reflux in control subjects and in those with peptic ulcer is discussed, as is its relationship to the extent of vagotomy and the length of Roux-en-Y loops. Finally the diagnosis of biliary atresia using a similar radiopharmaceutical is described. It has been suggested that a high liver to heart ratio excludes the diagnosis of atresia, but we have failed to confirm this finding.