The genus Calomyscus has long been considered monotypic and represented by the species C. bailwardi. Finally in the most recent revision, eight geographic species were recognized: C. bailwardi, C. baluchi, C. elburzensis, C. grandis, C. hotsoni, C. mystax, C. tsolovi, and C. urartensis. Since the taxonomic status of this genus remains somewhat controversial, karyological analysis may provide important information for evaluating the systematic position of Calomyscus. So far, within the range of the genus Calomyscus several distinct karyotypes have been identified. The karyotype of C. hotsoni has been undocumented until now but its karyotype recorded in this study from vicinity of type locality, Sistan va Baluchistan Province in the south eastern of Iran that was different with the karyotype of another species in this genus. Furthermore, three new karyotypes of Calomyscus were studied by conventional staining technique from Khorasan and Yazd Provinces of Iran that represent chromosomal variations in this genus. Chromosome studies show that Calomyscus specimens from Yazd Province should be belong to C. elburzensis. But more karyological, molecular and morphological studies would be necessary for confirming this decision.