This article is intended to clear up a few scattered points in the natural history of warts and to ascertain the types of therapy in common use today. Warts are autoinoculable and transmissible.1The incubation period after experimental inoculation varies from one to twenty-one months and averages four months. It has been demonstrated that infection by a virus causes warts, and this observation has been confirmed by a number of investigators.2 Warts occur not only in human beings but in cattle, dogs and rabbits.3The viruses causing warts are, in general, species specific; hence it is not possible to acquire warts from contact with an infected animal. Wart viruses are not only species specific but also epitheliotropic; that is, they invade only cells of epithelial origin. In rabbits, two separate viruses have been isolated, one of which causes cutaneous warts4and the other warts of the