Arthropods and their products are wide spread and considered one of the common allergens affecting man. Allergy to arthropod antigens is the major cause of respiratory allergy as rhinitis and bronchial asthma. The range of reaction depends on several factors which include the type and source of the material, the rate of intensity, the duration of exposure, the human immune response and history of prior exposure. Successful management of allergic disease depends on proper identification of the causative allergen and reduce exposure to this allergen. Generally speaking, the house dust is not a simple substance but an accumulation of living and non living parts as mites, pollens, molds, dander and decaying insects. In the present study, four species of mites were isolated from the dust collected from the houses of patients with allergic respiratory diseases. The species were Dermatophagoides pteronyssinus, D. farinae, Ornithonyssus bacoti and Haemogamassus pontiger. The two species of Dermatophagoides. were the predominant mites which are known to produce the most potent allergies. Studying the serum immunoglobulins level showed that the IgE had a highly significant concentration among respiratory allergic patients (28) with (5) or without (23) atopic dermatitis. It was concluded that house dust mites, that cause inhalant allergens, are one of the main aetiological factors of allergic respiratory diseases, with or without atopic dermatitis.