The effectiveness and safety of bunamiodyl, given by mouth for purposes of cholecystography, were studied in 500 patients. Given in a total dose of 4.5 Gm. in six capsules on the evening before the examination, bunamiodyl afforded fair, good, or excellent visualization of the gallbladder in 364 and poor visualization or none in 136 patients. In this dosage it caused nausea in only 14% of patients. In 23 patients whose progress it was possible to follow after the examination, a roentgenographic diagnosis of cholecystitis, cholelithiasis, or both, was confirmed at surgery in every case. Compared with other contrast mediums used, bunamiodyl in the above dosage caused less diarrhea and dysuria. There was also less difficulty with unabsorbed radiopaque residues in the intestine which tend to confuse the reading of the roentgenograms.