The study presented in this research paper is the first taxonomic investigation focusing on Uropodina (Acari: Mesostigmata) mites with a brief discussion of the genetic differences of two very closely related species from the genus OodinychusBerlese, 1917, i.e. O. ovalis (C.L. Koch, 1839) and O. karawaiewi (Berlese, 1903). These two morphologically similar species are quite common and they have a wide range of occurrence in Europe. They also live in almost the same types of habitat. However, O. ovalis usually exhibits higher abundance and frequency of occurrence. The major aim of the study was to carry out a comparative analysis of the systematic position, morphological and biological differences, as well as habitat preferences and distribution of O. ovalis and O. karawaiewi. The next aim was to ascertain whether the differences in number and frequency of these species may stem from the genetic differences at the molecular level (16S rDNA and COI). The study shows that O. ovalis, which is a more abundant species than O. karawaiewi, turned out to be genetically more polymorphic.