The genetic polymorphism of the beta-lactoglobulin gene was investigated in 182 sheep of Turkish fat-tailed sheep breeds by using PCR-RFLP methods. In the study, two alleles (A and B) and three genotypes (AA, BB and AB) at beta-lactoglobulin locus were observed. The most common genotype at the beta-lactoglobulin locus was AB. The greatest frequency of allele A was detected in Tuj breed as 0.7188. Results of the present study show that genetic polymorphism exists in the Turkish fat-tailed sheep breed population used in this study.