New data was added to the oribatid species composition of the Rivnensky Nature Reserve. Overall, 62 mite species were recorded for the territory of research in this study. The species Acrogalumna longipluma, Micreremus brevipes, Licneremaeus licnophorus, Oribatella reticulata, and Porobelba spinosa were not previously listed for the Western Polissia. Of the 60 species of Lower Oribatida mites that have been recorded by other authors in that area, only 18 are found again in the Rivnensky Nature Reserve, indicating that our results are intermediate. A representative of the genus Mainothrus Choi, 1996 (Mainothrus badius (Berlese, 1905)) is found in Ukraine for the first time.