Creation of interspecific hybrids is widely common among plants and animals in order to improve economically important traits for humans. The studied material consisted of chromosomal preparations in the metaphase stage obtained from interspecies hybrids of arctic foxes (Alopex lagopus) and red foxes (Vulpes vulpes). The aim of the study was to analyze the karyotype of the interspecific hybrids taking into account the number of chromosomes of sets A and B. With the use of techniques of classical cytogenetics (C bands, AgNOR bands) and molecular cytogenetics (FISH, PRINS) we carried out a genome analysis of Alopex-Vulpes hybrids. The results of this study showed that chromosomal markers of the interspecies hybrids are inherited from the parent species and are a result of combination of their two genomes. However, intraindividual differences are also observed which may result from aberrations of chromosome segregation during embryonic development. This may lead to the formation of different cell lines with different karyotypes (mosaicism). Moreover, chromosomes of the interspecies hybrids showed telomeric signals at the ends, in the centromers, as well as short chromosome arm rich in heterochromatin. The use of PRINS method led to identification of nucleolus organizer regions on 12 chromosomes of the interspecies hybrids. The hybridization signals obtained were characterized by different size and intensity. In addition, single copies of rDNA in the centromeric regions of several metacentric chromosomes were identified.