The Karyotypes asymmetry / symmetry of one taxon (10 populations) from different geographic sites of the genus Thymus are presented. The ploidy level varied between populations belonging to T. eriocalyx (2x and 4x), According to intrachromosomal asymmetry T. eriocalyx (T8: Population No.8 and T9: Population No.9) had the most asymmetrical and evolutionary karyotype and T. eriocalyx (T2, T4 and T10) had the most symmetrical karyotype in all of the populations. Based on interchromosomal asymmetry, among diploid populations, T. eriocalyx (T2) and among tetraploid populations T. eriocalyx (T7) had the most asymmetrical karyotype. In terms of the Stebbins’ system, the karyotype of populations can be classified in 1A and 1B classes. The results of analysis of variance revealed significant differences between the populations based on all karyotypic characteristics (P<0.01 and 0.05). The results of cluster analysis showed that the populations of T. eriocalyx have been grouped in separate clusters. The results seemed to provide enough genetic evidence to identify the populations and useful data to clarify the interspecific relationships. Results of karyotype analysis allow us to group the different populations and to specify their relationships.