Specific microclimate is often present in livestock buildings, which creates conditions suitable for the invasion and development of various microorganisms. From the sanitary-epidemiological point of view, the presence of even potentially pathogenic bacteria, and in particular fungi and their metabolic products, may endanger human life and health and the livestock. The aim of this study was to characterize microbial quality of livestock buildings in farms. The air samples were collected in farming buildings, such as cow houses, hen house, barn and granary. Bioaerosol samples were collected using a six-stage Andersen impactor. During sampling, air relative humidity (RH) and temperature were measured with thermohigrometer Kestrel 4000. Qualitative evaluation of the air microflora isolated from air revealed that the dominant microorganisms were bacteria from the genera Staphylococcus, Micrococcus, and Bacillus and fungi: Alternaria, Aspergillus, Cladosporium and Penicillium. On the basis of the results it was found that the highest concentration of bioaerosol was in buildings where sanitary standards were not met – animal faeces were not removed, air humidity was above 70% and the ventilation was insufficient.