Milk of calcium bile is a rare disorder in which the gallbladder lumen is filled with a semisolid radiopaque material composed primarily of calcium carbonate. The etiology is unknown, although gallbladder stasis is believed to be a prerequisite. We report a case of milk of calcium bile in which preexisting gallbladder stasis was retrospectively evaluated by reviewing plain abdominal films and by using iodide as a marker for retained contrast. This latter approach was validated by demonstrating that obstructed gallbladders do not physiologically sequester iodide and that following oral cholecystography functioning gallbladders do not retain significant iodide for prolonged periods. In the case described, we propose that gallbladder stasis was present as long as 2 1/2 years prior to the diagnosis of milk of calcium bile.