Following endoscopic gastric juice aspiration, intragastric bile acids were measured in 105 patients undergoing routine or review gastroscopy. Subsequently, duodenogastric reflux was assessed using 99mTc butyliminodiacetic acid (BIDA) scintigraphy and intragastric bile acid levels compared with the grades of reflux assessed scintigraphically. There was a significant correlation between both free and total intragastric bile acid levels and the degree of radiological bile reflux, especially when reflux was severe. Both endoscopic measurements of bile acids and BIDA scintigraphy appear to be useful methods for determining duodenogastric reflux, but neither may be accurate enough to quantify minor degrees of reflux.