E XPLORATION Of the extrahepatic biliary system is a common problem encountered in abdominal surgery today. Accurate presurgical information regarding the type and severity of the pathologic condition as well as the exact anatomic location of the lesion would be very beneficial to all surgeons preparing to operate on the extrahepatie biliary system. This article will briefly review the history of percutaneous transhepatic cholangiography (PTC) and delineate its usage in our experience; it will indicate the major benefits obtained in eleven consecutive patients with extrahepatic biliary obstruction and on whom PTC was performed. Most of these patients are elderly and considered poor surgical risk; thus, having reliable advance information at a minimal risk is doubly rewarding. The usefulness of PTC is further augmented in moderate to severe jaundice when standard excretory eholeeystography and cholangiography have not visualized the biliary system.