Cholecystography is being used so extensively to test the function of the gallbladder that it was considered advisable to compare the evidence of the cholecystogram with the pathologic changes in the gallbladder after its removal. We have studied every case available. The department of roentgenology has examined the gallbladder, after administration of tetraiodophthalein, in 662 clinic patients. Cholecystectomy was done later in forty of these. The other ten patients were seen in private practice. In thirty-two of the cholecystograms the dye (3.5 Gm. of tetraiodophenolphthalein sodium) was given intravenously. In the early tests, films were taken three hours after administration of the dye. In later tests the interval was ten hours, and in the most recent tests fifteen hours. In the other eighteen cholecystograms the dye was given by mouth with the evening meal, 5 grains (0.3 Gm.) to each 10 pounds (4.5 Kg.) of body weight, and the films