Postvaccinal eruptions, according to Danziger,1 were first collectively studied and classified in 1881 by Behrend, who described erythematous, urticarial and herpetic dermatoses as well as the pustular eruptions termed vaccine generalisée by various French writers. Since then the literature relevant to vaccinia in general has become voluminous. The purpose of this discussion is not to review these contributions completely but rather to attempt to clarify the confusion which exists as to the relationship of generalized vaccinia, eczema vaccinatum, Kaposi's varicelliform eruption (eczema herpetiforme) and pustulosis vacciniformis (varioliformis) acuta. A considerable number of cases of eczema (especially of the face and scalp) or some other itching dermatosis complicated by an acute eruption of umbilicated pustules occurring shortly after vaccination or contact with a vaccinated person have been reported under the title of eczema vaccinatum or, when the lesions were more widely spread over the cutaneous surface, generalized vaccinia.