By epicutaneous skin test by means of 1-monochlorine-2,4-dinitrobenzene (DNCB) the primary cell-conditioned immunity is induced and is provable by the allergic skin reaction of late type. The examination of 125 clinically healthy persons of either sex at the age of 17-57 years confirms the suitability of self-produced, welded into foil skin test plasters layered with DNCB in various stages of concentration for clinical use. A 48-hour skin contact with 0.049 molar DNCB-solution (1,000 microgram DNCB: 100 microliter Ol. oliv.) leads to a late reaction in 84% of the cases, in the repeated case in 98% of the cases. The valuation of the eczema-typical symptoms is suitable for the characterization and quantification. There were no differences in age and sex. Ultrastrong reactions were not registered.