¹Department of Agricultural Biotechnology, Faculty of Agriculture, Eskişehir Osmangazi University, TR-26160, Eskişehir - TURKEY DOI : 10.9775/kvfd.2017.18769 Avian leukosis viruses (ALV) are retroviruses that can induce tumors in chicken. Typically, ALV is controlled through husbandry. However, genetic improvement and/or, selective breeding techniques, offer the unique possibility of true resistance. The tumor virus B (TVB) locus transcribes the cellular receptor that mediates an infection through B, D, and E subgroups of avian leukosis virus. Two single nucleotide polymorphisms (SNPs) at nucleotide positions 172 and 184 of the TVB locus account for the three major alleles, TVB*S1, TVB*S3, and TVB*R. The receptor encoded by TVB*R allele prevents viral entry into the cell of ALVB, ALVD, or ALVE subgroups. In this study, both SNPs at the TVB locus of Turkish native chicken breeds were investigated using a PCR-RFLP technique to detect. In both Gerze and Denizli breeds, the TVB*S1 allele was common and TVB*S3 was rare, respectively. The TVB*R allele was rare in the Gerze population and absent in the Denizli population. Allele frequencies of TVB*S1, TVB*S3, and TVB*R were evaluated as 0.96, 0.02, and 0.02 in Gerze chickens and 0.98, 0.02, and 0.00, in Denizli chickens, respectively. Keywords : Denizli cocks, Gerze fowls, PCR-RFLP, Tumor virus B locus