Summary: Domestic dust is a well-known source of numerous respiratory allergens, such as: house dust mites allergens or insects allergens, mould spores as well as the saliva components, exfoliated epidermis, excreta of breeding animals and others. In case of people having the atopic symptoms to house dust mites allergens, the all year long exposition contributes to the respiratory tract diseasesí development. In order to decrease the level of exposure to house dust mites allergens’ inhalation in apartments of selected group of allergic patients Allergoff was used, which is based on technology of microencapsulation. The tests results clearly indicate the significant decrease of the concentration of the main allergen of Dermatophagoides pteronyssinus (Der p 1), the substantial reduction of clinical symptoms of allergic rhinitis and conjunctivitis and also the decrease in usage of anti-allergic treatment and salbutamol in comparison to baseline assessment. This project was accepted by Bioethical Commission of Medical University of Silesia in Katowice.