Bromus danthoniae is a rangeland grass with growth potential in mountainous slopes and harsh desert climates. In this respect, it is known as a tolerant plant which is suitable for desert areas and even saline areas. However, the genetic diversity in Iranian samples of this species has not been studied using molecular markers yet. The present study was performed with the aim "to evaluate the genetic diversity of B. danthoniae genotypes collected from saline and non-saline regions of the west of Iran using microsatellite markers. The plant material used in this study included 79 genotypes of B. danthoniae , which were collected from western and northwestern regions of Iran. The genetic diversity of the genotypes was evaluated using 12 polymorphic EST-SSR and SSR markers. First, each of the primers was tested through polymerase chain reaction by the DNA of some geographically distinct genotypes, and then the polymorphic marker was applied on all genotypes, if there was any polymorphism. The results showed that Xtxp-12 and Xcfd9 primers were more successful than other primers in explaining the genetic distance of the genotypes used in this study. The average Polymorphism Information Content (PIC) generated by primers used in this study was 0.472, which produced moderate polymorphism among the genotypes. Based on the clustering diagram performed, based on the data obtained from the EST-SSR and SSR markers, eight groups were obtained, which had a fairly good agreement with principal coordinates analysis (PCoA) results. Based on similarity matrix of genotypes, two genotypes NAG6-C and NAG2-C with the similarity coefficient of 84% had the most and two URM11-D and ILA1-G genotypes with the similarity coefficient of 17% had the least similarity. In the resulting classifications, there was an incomplete correlation between genetic diversity and geographical diversity. The results obtained from the principal coordinates analysis for both EST-SSR and SSR markers showed that the first five components totally justify 58.28% of the total variation. In the EST-SSR and SSR markers, the Fst value was 0.0535, indicating a moderate difference between the studied groups. The results of molecular variance analysis showed that 5.36% of the total variation has been allocated among the geographical groups and 94.64% of them has belonged within the groups. The results of genetic distances and similarity coefficients in the EST-SSR and SSR markers showed that the highest similarities were between West Azarbaijan genotypes -15 km from Urmia (E) and West Azarbaijan-Mahabad road-Naghadeh (0.95) (C) and the lowest belonged to genotypes of West Azarbaijan-Mahabad Road-Naghadeh (C) and Marivan-Iran-Iraq border (0.72) (O). In the resulting classifications, the studied genotypes that belong to a geographical area did not include in one group and grouped along with genotypes from other geographical region. The reasons that can put forward to explain are the migration of seeds by animals, birds and environmental factors. The high genetic diversity identified among and within the geographical groups and Bromus danthoniae genotypes indicate the rich germplasm of Bromus genotypes in Iran. This rich genetic resources that adapted to stressful environments, especially salinity, drought and heat, can be used to improve economically important relative crops such as wheat and barley through molecular breeding. Keywords : molecular marker, genetic variation, polymorphism, genetic distance, pure line