Arbitrary oligonucleotides were used as primers to amplify genomic DNA of 48 wild Spanish populations of Agropyron cristatum, Elymus hispanicus, E. caninus, E. repens, Thinopyrum curvifolium, Th. junceum and Th. intermedium. Genetic diversity was analysed using nineteen primers. The number of amplified products ranged from 8 to 18 per primer and a total of 240 markers were scored. Different levels of intraspecific genetic diversity were found, the allogamous species E. repens and Th. intermedium being the most variable. Jaccard's similarity coefficients for internal measure within and between populations were used to produce a cluster diagram. The results demonstrate differences in the degree of similarity between taxonomic units. Interpopulational variability and interspecific genomic relationships of these species are discussed.