During a recent discussion with Dr. I. R. Jankelson about his work with sodium dehydrocholate in cholecystography,1 it occurred to me that this drug, owing to its choleretic action, might be of value in prevention and treatment of damage to the liver by arsphenamine and other arsenicals. As a result, I have studied the effect of sodium dehydrocholate in patients who have shown such toxic reactions. That the liver is the principal organ concerned in the metabolism of the arsenicals, is well known. Osborne and others,2 in a recently reported series of experiments on rabbits, have shown definitely, by means of microchemical studies, that: 1. Arsphenamine in therapeutic doses is rapidly metabolized in the liver. 2. After a lethal dose of arsphenamine, the liver contains a maximum amount of arsenic and is apparently the only organ of storage. 3. One hour after a lethal dose of