Background:Bovine spongiform encephalopathy (BSE) is a prion disease that is always fatal in cattle and is considered an important risk factor for human health. Genetic polymorphisms that alter prion proteins may be associated with susceptibilityor resistance to infectious spongiform encephalopathy. Therefore, we investigated the distribution of the 23 bp indel variant in the prion protein (PRNP) gene in Jersey cattle in Turkey.Methods:A total of 95 unrelated Jersey cattle (79 of reproductive age and 16 of non-reproductive age) from a private farm in Izmir were included in the study. Genomic DNA was obtained from the milk of reproductive-age cattle and the saliva of non-reproductive-age cattle. A 23-bp indel polymorphism in the PRNPgene promoter region was genotyped by polymerase chain reaction (PCR) analysis.Results: The three genotypes of the PRNP 23-bp indel variant were classified as follows: I/I (223 bp), I/D (both 223 and 200 bp fragments), and D/D (200 bp).. The frequencies of the I/I, I/D, and D/D genotypes of the PRNP 23-bp indelvariant in cattle were 22 (23.16%), 48 (50.53%), and 25 (26.32%). We then examined genotype and allele distribution according to service period. No significant difference was detected in terms of PRNPgene 23 bp-indel variant genotype and allele distribution in the groups created according to the service period (p>0.05).Conclusion:Although the PRNPgene 23 bp-indel variant genotype and allele distribution in jersey-type cattle in Turkey did not differ according to service period,our results may benefit the understanding of the genetic characteristics of the PRNPgene in cattle breeds.Key words:Bovine spongiform encephalopathy, prion protein, variant, PCR.