Skin diseases caused by contact allergies are non-critical as a rule. For the person affected, however, they mean a profound diagnosis with partly considerable consequences. Occupationally and non-occupationally acquired contact allergies constitute a not inconsiderable economic cost factor. Benefits having to be paid by professional associations only for occupationally induced skin diseases run into more than 125 Million Euros per year. As a rule, once acquired contact allergies persist all one’s life and to this day there is no way of curing them. Thus, the only effective measure in this field is prevention which splits into primary prevention in the sense of preventing creation of new contact allergies, and secondary prevention in the sense of avoiding contact with allergens in the case of an already existing allergy.Through cooperation of numerous clinics of dermatology is has become possible to record large collectives of patients within a short space of time. By this, newly appearing allergens can be more quickly registered and made public as “sentimental health events” and decision-makers can be induced to intervene respectively.Analysis of sensitizations in subpopulations, whose observation in separate clinics would take years, lets us more easily detect risk groups and makes it possible to give advice to the already sensitized.