House dust mites play an important role in the pathogenesis of allergic diseases. Both the common species of the genus Dermatophagoides viz. Dermatophagoides pteronyssinus and D. farinae and other two allergenic species Blomia tropicalis and Austroglycyphagus geniculatus are found to be abundant in the dust samples collected from beds of patients suffering from nasobronchial allergic disorders residing at Kolkata metropolitan areas. The presence of these four mites in large quantity in the patients environment are clinically correlated with the aetiopathology of various allergic manifestations like allergic rhinitis, bronchial asthma etc. House dust mites usually occupy different niches in the homes of asthmatics and are significantly higher in beds than else where in the house. However, the distribution and abundance of these mites are influenced by several microclimatic conditions. The aim and objective of the present study is to assess the impact of different microclimatic conditions like type of houses, type of mattresses and bed and floors of the room on the distribution and abundance of house dust mite population. In view to provide the patients with best possible diagnosis and treatment, proper identification of offending allergens and their subsequent reduction from the patient's environment is of outmost importance which in turn may be helpful for the prophylactic management of these dreadful diseases in Kolkata metropolis. © Acarina 2010.