Scintigraphy was performed on 180 patients with suspected biliary tract disease using technetium-99m-labelled derivatives of iminodiacetic acid. Most of the patients were also evaluated by conventional techniques and the results were correlated with the findings at operation and with histological examination of tissue removed whenever indicated. The technique was very accurate in the diagnosis of acute cholecystitis. In chronic cholecystitis it was useful in the diagnosis only when the cystic duct was obstructed. Scintigraphy has no value in the diagnosis of gallstones. However, it permits visualisation of the biliary tract even in the presence of jaundice and is useful in distinguishing obstructive from non-obstructive types of jaundice.