Summary Percutaneous transhepatic cholangiography has been performed by introducing contrast material through a polyethylene catheter into the liver. This catheter may be left in situ after the cholangiogram, permitting biliary drainage and so reducing the risk of biliary peritonitis. In 24 of 30 patients with the clinical picture of obstructive jaundice a bile duct was punctured and bile was aspirated. In 22 of these patients cholangiograms demonstrated obstruction to main bile ducts. In the other 6, no bile ducts were f ound and in 4 of these subsequent operative cholangiography demonstrated no intrahepatic biliary dilation. These 6 patients were believed to be suffering from primary biliary cirrhosis. The only complication was biliary peritonitis confirmed at subsequent operations upon 2 patients in whom a bile duct was punctured. Surgery was, therefore, always perf ormed on the same day in all of the patients in whom extrahepatic biliary obstruction was demonstrated. The value of this technique in distinguishing intrahepatic from extrahepatic obstructive jaundice was discussed. It was concluded that the failure to puncture a dilated bile duct by this technique in patients with obstructive jaundice was strong presumptive evidence of an intrahepatic cause f or the jaundice. Where a cholangiogram was obtained an accurate prediction of the cause of the obstruction was made in all cases, including intrahepatic bile duct carcinoma, gallstones, carcinoma of the pancreas, and bile duct strictures. The value of this technique in planning reparative surgery in patients with bile duct strictures was discussed.