Microscopic fungi - components of bioaerosol found in the workplace environment of individuals employed in the agricultural sector - constitute a considerable hazard for their health. This study includes quantitative and qualitative analyses of mycobionta contained in 20 samples of dusts collected from laboratories conducting analyses of cereals. A total of 27 species of viable microscopic fungi were isolated. The most frequently isolated genera Penicillium and Aspergillus, accounting for 27 percent and 26 percent of analyzed isolates. The content of fungal biomass was determined quantitatively using a fungal marker, ergosterol (ERG). Concentrations of this metabolite for all samples ranged from 0.48 mg/kg-212.36 mg/kg. Based on the analyses, it may be stated that the concentration of microfungi in settled dust from laboratories conducting analyses of cereals was varied, and in several cases markedly exceeded admissible concentration levels.