Аннотация:Studying the conditions of propagation of micromycetes in living quarters is very important due to the diverse influence of fungi on human health. The availability of water is the key factor limiting the growth of micromycetes. The effect of water activity (aw) and RH on germination and growth of the fungi isolated from living quarters of Moscow city was studied. Following species were tested: 1) 10 dominants, Alternaria alternata, Aspergillus repens, A. sydowii, A. versicolor, Cladosporium cladosporioides, Penicillium chrysogenum, P. cyclopium, P. glabrum and one rare species, Trichoderma viride, 2) two spices which form associations with house dust mites, Aspergillus penicillioides, Wallemia sebi, 3) frequent food contaminant Mucor racemosus. Solid media with aw values from 0.99 to 0.65 and house dust at RH from 99% to 65% were used. All examined fungi except T. viride were able to undergo a complete life cycle A. alternata, A. sydowii, A. versicolor, C. cladosporioides, P. chrysogenum, P. cyclopium, P. glabrum appeared to be xerotolerant due to their ability to germinate at 0.99-0.85 aw and 99%-85% RH with preference of 0.99 aw and 99% RH. M. racemosus, T. viride are hygrophiles incapable to grow at aw below 0.95, and A. repens, A. penicillioides, W. sebi are xerophiles, which grow at 0.99-0.75 aw and 99%-75% RH, preferring 0.95 aw. We conclude that research of the influence of aw and RH on micromycete growth is necessary for planning preventive measures.