When upper abdominal symptoms persist or recur after cholecystectomy, the possibility of stones being present in the common bile duct usually arises. Examination which will give positive evidence as to the presence or absence of such stones is obviously valuable. Both diagnostic transduodenal biliary drainage and intravenous cholangiography are of real help in this problem, but each has certain limitations. It is often necessary, therefore, to correlate data from both of these tests with the clinical evaluation of the patient before a reasonable decision can be reached regarding the advisability of surgery. Our experience with these two diagnostic examinations forms the basis of this report. Diagnostic Transduodenal Biliary Drainage To determine the diagnostic value of biliary drainage in detecting postcholecystectomy biliary lithiasis, we reviewed the records of all patients on whom exploration of the common bile duct was carried out from 1935 through 1955. Of this group of 580 patients,