Genotyping of Turkish grapevine (Vitis vinifera L.) germplasm was characterized by use of six highly polymorphic microsatellite loci (VVS2, VVMD5, VVMD7, VVMD27, VrZAG62, VrZAG79). In this study we aimed to clarify the relationships between homonymous varieties coming from different regions. Our results showed a large degree of genetic variability among most of the homonymous cultivars. The number of alleles per locus ranged from 10 to 21, and gene diversity (expected heterozygosity) values ranged from 0.85 to 0.93. Cultivars presenting the same names of Sergi karasi (sampled from Sanhurfa and Gaziantep), Yediveren (sampled from Sanhurfa, Gaziantep, and National Germplasm Repository Vineyard in Tekirdag) and Serpenekiran (sampled from Sanhurfa and Gaziantep) were clustered together, or very close to each other, in a phenogram. Moreover, the alleles at the six microsatellite loci analyzed were found to be similar in terms of base pairs within each of these three closely positioned varieties. However, all the other cultivars failed to show a suitable clustering pattern when comparing their DNA profiles and names. Similarly named cultivars were not generally grouped together in the phenogram. On the other hand, we detected a tendency for differently named homonymous grape cultivars to cluster together. (C) 2007 Elsevier B.V. All rights reserved.