Forty-six patients were selected for further study after routine cholecystography had failed to give satisfactory visualization of the gallbladder or bile ducts. When oral cholangiography was carried out in this group, there was visualization of the gallbladder or of the common bile duct with stones in 23 patients, visualization of the gallbladder without stones in 12, and no visualization in 11. Of these 11, 8 were operated on and were found to have obstructed cystic ducts. Three of these had acute cholecystitis, with gangrene in one. Nine patients were spared an operation when oral cholangiography demonstrated normal function and absence of stones in the gallbladder. Resort to oral cholangiography is therefore to be recommended when routine cholecystography fails to give decisive results, for it gives 65% additional visualization as compared to only 5 to 10% additional visualization with the double dose method.