Thirty years ago, Graham and Cole1 published their report on a new method of visualization of the gall bladder based on the fundamental work of Abel and Rowntree.2 Now, for the first time, a new substance is available, Cholografin, which, when administered intravenously, will produce roentgenographic visualization of the common bile duct in the presence or absence of the gall bladder.* Cholografin is an isotonic and colorless solution of the disodium salt of N,N′-adipylbis (3-amino-2,4,6-triiodobenzoic acid) with the empirical formula C20H12O6I6Na2. When first prepared by Schering, it was called Biligrafin. It contains 64% iodine which is molecularly stable and firmly bound even after injection into the blood stream. Cholografin is promptly and rapidly excreted by the liver. Its concentration in the common and hepatic ducts is sufficient for roentgen visualization within 20 minutes after intravenous injection (Fig. 1). A