House dust allergy and house dust mite allergy are with 18.4 and 14.1% the most frequent causes of the atopic asthma also under our conditions. 2. In about 60% the house dust allergy is conditioned by a sensitization by constituents of mites (excretions). 3. The responsible antibodies may be established by means of the radio-allergo-sorbent-test. In about 50% results were found corresponding with the intracutaneous test. 4. In the restricted possibilities of the allergen carency the hyposensitization plays an important role. In critical choice of the patients in 50-60% a clinical improvement is to be achieved.