The edible dormouse (Glis glis) from Stolowe Mountains National Park (south-western Poland) was studied to reveal the genetic diversity of dormice living in the Polish Sudetes. Material (hair with roots) collected from 39 individuals (adults and juveniles) was used for genetic testing to perform population analyses. Molecular study involved two types of markers: nuclear DNA (11 microsatellite sequences) and mitochondrial DNA (fragment of cytochrome b of approximately 700 bp in length). Low genetic variability of the studied population was found. Two of the microsatellite loci proved to be completely monomorphic, whereas the degree of polymorphism of other microsatellites was also unexpectedly low. Only two haplotypes were found among all 39 individuals. Low genetic diversity of dormice from the Polish Sudetes, determined by genotyping of nuclear molecular markers, may be the consequence of fragmentation of this species’ population. Dormouse sites in Poland have been declining for decades due to deforestation and fragmentation of old forests. Therefore, dormice live in small populations in isolated habitats with increasing levels of homozygosity. Other possible causes of low genetic variability of G. glis are discussed as well.