Cholecystokinin (CCK) and its C-terminal octapeptide analog, Sincalide, have been utilized in two separate roles for the evaluation of gallbladder disease. These are: (1) prior to cholescintigraphy to evacuate the gallbladder and optimized subsequent filling with radiotracers, and (2) to study contractile function of visualizing gallbladders on cholecystography and cholescintigraphy. As a preparation for 99mTc-IDA studies, it clearly facilitates earlier gallbladder filling in patients with chronic cholecystitis, thereby ruling out complete cystic duct obstruction. The problem lies in the fact that the use of CCK as a premedication markedly decreases the sensitivity of the study to detect chronic cholecystitis, since the findings become indistinguishable from patients with normal gallbladders. For this reason, the authors prefer to obtain delayed images, since chronic cholecystitis is frequently associated with gallbladder filling beyond the first hour. The role of CCK in detecting abnormal gallbladder function in the normally visualizing gallbladder also is controversial. Other studies as well as the author's experience suggests that as much as one-forth of positive cases may be associated with normal gallbladders at surgery and often even on microscopic examination. However, most importantly, the great majority of these patients are relieved of their symptoms following surgery. It appears reasonable that CCK or Sincalide cholecystography or cholescintigraphy may be detecting functional abnormalities before anatomic changes occur and can, therefore, serve as a useful examination in selecting symptomatic patients who may benefit from cholecystectomy.