Cholescintigraphy with 99m-Tc labeled iminodiacetic acid (IDA) derivatives has proved to be extremely reliable in the evaluation of suspected acute cholecystitis. The major diagnostic feature of the study is the presence (cystic duct patency) or absence (cystic duct obstruction) of gallbladder visualization. Secondary findings include degree and rate of liver uptake, visualization and caliber of the intrahepatic and common bile ducts, and the presence of intestinal activity as well as rapidity of biliary tract-to-bowel transit of the radiotracer. Various combinations of these secondary parameters result in a spectrum of cholescintigraphic patterns which can assist in determining the cause of the patient's acute clinical problem.