We studied 88 attempts at cholangiography on 87 patients. Sixty were successful and we analyzed these in an effort to establish criteria for the differential diagnosis of bile duct pathology. Twenty-eight were unsuccessful; operative or T-tube cholangiograms were studied in 10 of these cases and biopsy results in 9, in order to determine the reason for failure and its inferential value. Seven of the 28 patients in whom cholangiography was unsuccessful were found to have obstructed bile ducts at operation.