In this study, gallbladder and gastric emptying were compared in 15 normal subjects and 15 patients with gallstones. A noninvasive technique which used two gamma-emitting radiopharmaceutical agents to image the gallbladder and stomach simultaneously was employed. Technetium-99m-HIDA was used as a gamma-emitting marker for the gallbladder and indium-111-DTPA was mixed with a standard liquid meal in order to stimulate gallbladder emptying and to measure gastric emptying. In patients with gallstones, gallbladder emptying was diminished significantly compared to normal subjects. In contrast, emptying of the stomach was normal. The gallbladder emptying responses to octapeptide of cholecystokinin, administered either as bolus or infusion doses, were similar in normal subjects and patients with gallstones. These studies suggest that gallbladder emptying may be abnormal in patients with gallstones. The explanation for this abnormality and its relationship to the development of gallstones has not been determined.