The character of the bile which is obtained at operation for obstruction of the common bile duct varies greatly. The most characteristic bile obtained is thick and dark green, but occasionally there is found so-called white bile. The type of bile obtained in each instance has prognostic as well as diagnostic significance. The important and fundamental problem related to the diagnosis is to determine the conditions that are responsible for the production of the different types of bile on different occasions. From the standpoint of the prognosis it is of vital importance to determine whether or not the liver is functioning normally when white bile is obtained. That this is still an unsolved problem is apparent when one reads the varying opinions expressed in the German and in the American literature concerning the prognosis. The German writers consider that the prognosis is much more serious when white bile is present.