This study reports for the first time the banding pattern on chromosomes of the Tatra vole, Microtus tatricus, as revealed by G-, C-, and Ag-NOR staining procedures. The banded karyotype of M. tatricus was compared with Microtus (Terricola) subterraneus, M. (Stenocranius) gregalis, and M. (Blanfordimys) aghanus. The karyotype of M. tatricus possesses highly derived features, e.g., the low diploid number of chromosomes or unique combinations of arms in the biarmed autosomes. It is almost impossible to find clear relationships of M. tatricus with other extant vole species from the point of view of comparative karyology. The karyotypic changes in voles are apparently not accompanied by adequate divergence in morphological and genetic traits.