Group reactions in patients sensitive to resorcinol are of considerable interest. In the first place, the allied chemicals and derivatives may be encountered in industrial and nonindustrial contacts, and some are of biologic importance. Second, such studies afford an opportunity to shed light on the relation of chemical configuration to cutaneous hypersensitiveness. Group reactions in this category have been investigated in part by a few observers.1,4 These studies have yielded data which have been sometimes interpreted as discordant, but actually the discrepancies are due to biologic variations in group reactivity. Thus, Bloch1 and Urbach,2 each in a single case, observed that patients hypersensitive to resorcinol gave milder, though definitely positive, reactions to pyroatechol and hydroquinone, whereas negative results were obtained with phenol and pyrogallol. In addition, Bloch found that phloroglucinol also gave a negative response. These observers were therefore impressed by this general hypersensitiveness to the dioxybenzols.