Species and genome relationships among 11 diploid (A and C genomes), five tetraploid (AB and AC genomes) and two hexaploid (ACD genome) Avena taxa were investigated using amplified fragment length polymorphisms (AFLPs) and random amplified polymorphic DNA (RAPD) markers. The two primer pairs used for the AFLP reactions produced a total of 354 polymorphic bands, while 187 reproducible bands were generated using ten RAPD primers. Genetic similarities amongst the entries were estimated using the Jaccard and Dice algorithms, and cluster analyses were performed using UPGMA and neighbor joining methods. Principle coordinate analysis was also applied. The highest cophenetic correlation coefficient was obtained for the Jaccard algorithm and UPGMA clustering method ( r=0.99 for AFLP and r=0.94 for RAPD). No major clustering differences were present between phenograms produced with AFLPs and RAPDs. Furthermore, data produced with AFLPs and RAPDs were highly correlated ( r=0.92), indicating the reliability of our results. All A genome diploid taxa are clustered together according to their karyotype. The AB genome tetraploids were found to form a subcluster within the A(s )genome diploids (AFLPs), indicating their near-autoploid origin. The AC genome tetraploids are clustered to the ACD genome hexaploids. Finally, the C genome diploids form an outer branch, indicating the major genomic divergence between the A and C genomes in Avena.