Specific reactions by the human skin to certain organic substances are important aids in diagnosis. Skin tests with air borne and food proteins, as guides in determining the exciting causes of asthma and allied disorders, have found a place in company with the Schick, the luetin and the dermal tuberculin tests. Less attention has been directed toward tests with bacterial vaccines in the infected and hypersensitive patient; indeed, their importance has been questioned. A few investigations in vaccine skin testing have been published by others, who report suggestive but confusing results. The difficulties encountered in making an adequate study of this problem from the bacteriologic standpoint have, perhaps, accounted for some of the earlier failures. On beginning the study of a case of asthma or allied disorder, air borne and food proteins as etiologic factors should be eliminated, if possible, by proper skin tests. Positive skin reactions to one or