This article presents results of research on the effectiveness of three types of air purification devices in scope of reducing the total number of bacteria and the total number of fungi. The tested devices used the following purification technologies: Device A – cold plasma generator and mechanical air filtration, Device B – multi-stage mechanical filtration and photocatalysis process, Device C – UV-C flow lamp with carbon filter. The total number of bacteria and fungi in air samples was determined using impact method. The measurements were performed before the devices started to work, during air purification and after the end of the process. The analyzes were carried out in real conditions: one device was used in a pre-Intensive Care Unit room at the Accident and Emergency hospital department, the two others were tested in office rooms. Obtained results show, that the effectiveness of air purifiers in reduction of the total number of bacteria and fungi tested in real conditions was lower than the effectiveness declared by purifier manufacturers. The use of air purifiers to improve indoors air microbiological quality should always be preceded by the appropriate selection of the device. It should take into account the parameters of the target room and the number of people staying in it.