In recent years ringworm of the scalp has assumed a position of considerable importance in the United States. It was formerly unnecessary for most physicians to be familiar with the problem because of the rarity of the epidemic form in this country, but recently epidemics have spread the disease widely throughout the nation. Some forms of ringworm of the scalp spread rapidly, are capable of causing epidemics and are resistant to topical therapy. Because of the increasing number of cases of this type the problem has become one of public health, and protection of the community is as important as treatment of the individual. In 1822 Wilkinson1 recorded an epidemic in England. Cases have since been reported throughout the world, but the greatest incidence of the disease has been in France and in England. In 1843 David Gruby2 described the causative organism of epidemic ringworm and named it