Genetic resources constitute the building blocks of crop improvement programs. These provide the basic raw material as well as reservoir of genes for breeding high-quality cultivars. Characterization of germplasm is the prerequisite for subsequent utilization of the resources. In this study, suckers of twenty six Damask rose genotypes (Rosa damascena Mill.) were collected from some of the most important cultivation regions of Iran (Fars, Isfahan, Kerman and Azarbiejan provinces). These genotypes were planted at the Horticultural Research Center, University of Tehran based upon a complete randomized block design. For 2 years, 50 quantitative and qualitative morphological traits were evaluated to characterize the phenotypic variability. Analysis of variance revealed significant differences of characters accounting to the genetic variation in this species. Cluster analysis, using Ward's Method separated genotypes into 7 groups according to Squared Euclidian Distances. Fourteen genotypes stood in the first group indicating the high similarity of the most studied genotypes. These genotypes were mainly from Kerman, Fars and Isfahan provinces. However genotypes from East Azarbiejan formed a distinct and separate group. Within other genotypes, one with unique bushy growth habit (G3 from Tehran) and one with few prickles (G24 from Khorasan Razavi) were identified. Comparing mean deviation of quantitative traits of recognized groups in cluster analysis and regions’ comparison results revealed the weight of some distinct genotypes in making some provinces distinguishable for some traits. This study provided new insight into the germplasm of Damask roses in Iran being valuable for the design of constructive breeding programs.