The presence of bacteria and fungi in indoor air pose a serious problem from the point of view of health protection and environmental engineering. Precise determination of various groups of microorganisms indoors is necessary both to estimate the health hazard and to create standards for indoor air quality control. This is especially important in such densely populated facilities like education objects. In this study the level of microbial contamination in rooms of kindergarten, primary school and high school was estimated. A level of microbial air pollution was stated as a considerable high, compared with existing suggestions for microbiological standards and UE demands. The number of microorganisms (as CFU/m3) ranged within 340-7530 for mesophilic bacteria, 5-35 for haemolytic bacteria, 25-475 for staphylococci, 0-45 for coli group bacteria and 30-785 in the case of moulds.