Abstract. In this study the genetic diversity of morphological traits in Elymus tauri,seeds of 12 populations from East Azabaijan,Ardabil, Kordestan and Alborz provinces were collected. The seeds were planted in Randomized Complete Block Design(RCBD),with four replication, in Tabriz Botanical Garden.Analysis of Variance showed that there was a significant difference among populations at %1 probability level in all traits under study. Cluster Analysis of data based on Ward method,differentiated 12 populations in 2 groups.In Principal Component Analysis,the contribution of the first and second components was higher than %73.In the explanation of the first component,the traits of total number of tillers,spike length and fertile tiller numbe had high positive and significant rates.Grouping obtained from Cluster Analysis was confirmed with the results of Principal Component Analysis.Keywords:Cluster Analysis,Elymus tauri,Genetic Diversity,Principal Component Analysis