Factors stimulating the development and spread of micromycetes in buildings used for different purposes were investigated. A variety of materials are used for reconstruction and building: timber, shied-shaped assembled houses, air-entrained concentrate, other local materials, monolithic (expanded clay concrete) houses, large-slab houses, silicate bricks, ceramic building bricks, including special front trim (clinker, restoration, etc.). Resistance of the construction materials to biological factors is not evaluated; the interest is raised only when some concrete damage is encountered. Dampness in buildings is a common reason for a variety of health symptoms in the inhabitants. From inside walls of such buildings the fungi of the Aspergillus genus, mostly A. fumigatus, A. niger, A. penicillioides less frequently of other species were isolated. They are active producers of various metabolites, able to participate in decay processes of various materials. Conditionally pathogenic fungi were found in all the buildings investigated. Their abundance and the variety of species depended on the physical condition of the buildings, their age and the nature of the specific activities which were carried out in them. Keywords: buildings, materials, fungi, destruction, human health.