This motion picture illustrates the technical points that have been adopted by us in developing practical operative cholangiography in conjunction with cholecystectomy. Close cooperation of the radiologist and the surgeon in an endeavor to eliminate all possible sources of error attains a greater degree of accuracy in diagnosis of common duct stones than surgical exploration or palpation alone. When this procedure is performed carefully and interpreted with the accumulated experience of past performance, it is dependable, frequently obviating common duct exploration in otherwise doubtful cases. The dependability will vary with the interest and ability of the professional team, the availability of equipment, and the frequency with which operative cholangiography is practiced. The surgical technique of cholecystectomy is well demonstrated in the film. The indications and judgment in three different circumstances are emphasized.