Silver arsphenamin, the latest of the arsphenamin series of drugs, is now on the market, and is being used in America. There is no English literature to guide one in determining its qualities. Our communication is an effort to review the literature on silver arsphenamin and to draw conclusions therefrom. Silver arsphenamin was suggested by Ehrlich, whose untimely death cut short his researches, which were continued by Kolle who finally elaborated silver arsphenamin. This drug was first used clinically in March, 1918. Kolle,1 in 1918, in the first of a series of articles, gives the following table which shows that silver arsphenamin had a more profound effect on experimental syphilis than any of the other members of the arsphenamin group. He concludes from his work that silver when combined with the arsphenamin molecule forms a combination which has a greater spirocheticidal action than other combinations with which he worked. In his second article, published in 1919 Kolle,2 discusses at length the chemical properties of the drug and concludes that silver arsphena¬ min acts on the syphilitic process in a twofold manner : The arsphena¬ min molecule exerts its well-known spirocheticidal effect, while the presence of the silver radical seems to inhibit the growth of the spiro¬ chetes. Therefore, he says, silver arsphenamin acts in combination. Kolle,3 in 1920, reviewed the clinical results of various observers.