A chromosomal study of Allactaga euphratica from the Şanli{dotless} urfa Province in Southeast Anatolia, Turkey, was performed. The diploid number of 48 chromosomes was found in all four specimens examined. The C-bandpositive regions were distributed in centromeric areas of all the autosomal pairs and the X chromosome. Extensive C-positive heterochromatin intercalary blocks were observed in the largest pair of autosomes. The small Y chromosome was stained uniformly and C-negatively. The active nucleolus organizer regions (NORs) were localized in two pairs of small bi-armed autosomes. The C-heterochromatin distribution and localization of the secondary constrictions bearing NORs apparently differ between karyotypes of the related jerboa species A. euphratica and Allactaga williamsi. This cytogenetic difference may be implied as a suitable marker in further studies of the relationships in contact zones and possible hybridization between these two taxa. Copyright © 2011-2012 by Walter de Gruyter.