Controversy exists over the relation between gallbladder dysfunction and the propensity for duodenogastric reflux. To evaluate this, Tc-99m DISIDA hepatobiliary imaging studies in 120 patients were reviewed, excluding patients who had had cholecystectomy or subtotal gastrectomy before scintigraphy. Serial images were obtained at 5, 10, 15, 30, 45, and 60 minutes and up to 24 hours, if indicated, after intravenous injection of 5-10 mCi of Tc-99m DISIDA. Normally, the liver, bile ducts, gallbladder, common bile duct, and bowel are visualized sequentially. Reversal of the normal sequence of gallbladder (GB) and bowel visualization indicates GB dysfunction; nonvisualization of the GB reflects cystic duct obstruction or absent GB function. Duodenogastric reflux is identified by radiotracer localized in the area just below or immediately adjacent to the tip of the left hepatic lobe. The intragastric location of the tracer may be verified by oral administration of 300 uCi of Tc-99m sulfur colloid. Twenty-nine patients had duodenogastric reflux between 10 and 60 minutes after injection. Of the 29 patients, 22 had a nonvisualized gallbladder, four had reversal of appearance of GB and bowel activity, and three had a normal study. GB dysfunction or nonfunction is more frequently demonstrated when duodenogastric reflux is present than with normal gallbladder function (P less than 0.001). In conclusion, gallbladder malfunction is closely associated with duodenogastric reflux, an abnormality that may be diagnosed noninvasively by Tc-99m DISIDA hepatobiliary scintigraphy.