Russian wildrye (Psathyrostachys juncea Fisch. 2n=2x=14, NsNs) is an important forage grass and a potentially useful germplasm in wheat improvement. A standard C-banding karyotype of Ps. juncea has been developed based on the C-bands of chromosomes in geographically diverse materials. Although there are C-banding polymorph isms, the seven pairs of chromosomes can be distinguished from each other according to their basic banding patterns. Based on C-banded karyotype, one deletion-t ranslocation heterozygote, four primary trisomies, one double-deletion trisomic, and two tertiary trisomies were identified. These cytogenetic stocks will be useful in genetic studies of Russian wildrye. Genetic variations in Russian wildrye were analyzed at chromosomal, protein and DNA levels using C-banding, isozymes, and randomly amplified polymorphic DNA (RAPD) techniques, respectively. Due to the self-incompatibility in Russia wild rye, a high level of genetic diversity existed both within and among accessions. In general, accessions originated from the same or neighboring geographical areas showed closer genetic relationships. The results of various approaches for genetic variation analysis suggest that there are tremendous genetic variations in the Russian wild rye germplasm for the effective improvement of this forage grass. Some molecular markers were isolated and characterized in Russian wildrye using RAPD and cloning techniques. These markers may be useful in gene mapping, species identification, studies of evolutionary relationships, and transferring useful genes into cereal crops.