A method was developed which, by means of a prothesis fixed to the teeth, allows epimucous tests to be made without unnecessary irritations of the mucous membrane of the mouth. There are no parallels between the intensities of allergic contact reactions on the skin and the mucous membrane, when the concentration of the substance and the duration of its action are equal. The allergic reactions to mercury precipitate, anaesthesin and potassium bichromate on the skin were more intensive than those on the mucous membrane; whereas, the allergic reactions to chrome alum (0.5%) were faster and more intensive on the mucous membrane. Histogenetically the allergic reactions on the mucous membrane correspond to the eczematous allergic reactions according to Miescher.