It was aimed to investigate the genotypic structures of the Pit-1 gene from genomic DNA samples taken from Simmental and Brown Swiss breeds and determine the distribution of genotype and allele frequencies of bovine breeds and to determine the relationships between the detected genotypes and some performance traits. Pit-1/HinfI gene polymorphisms were determined using the PCR-RFLP method from genomic DNA obtained from Brown Swiss and Simmental breed cattle used in the study. According to the Hardy-Weinberg genetic test, the distribution of genotype frequencies of the studied population was found to be in equilibrium (p˃0.05) in both breeds. Genotype frequencies of AA, AB, and BB alleles of the Pit-1 gene were determined as 5.73%, 36.42%, and 57.85%, respectively, for Simmental breed, while the genotype frequencies for Brown Swiss breed were determined as 9.43%, 42.86%, and 48.01%, respectively. The actual milk yield for Simmental breed was determined as 5953 ± 364.2, 5212 ± 993.4, 5507 ± 889.5 kg, the 305-day milk yield as 5953 ± 276.8, 5642 ± 782.7, 5427 ± 246.7 kg, the lactation period as 307 ± 47, 293 ± 29, 303 ± 22 days, the daily milk yield as 19.53 ± 6, 18.49 ± 8, 17.81 ± 2 kg for AA, AB, and BB genotypes, respectively. The actual milk yield for the Brown Swiss breed was determined as 3606 ± 253, 3558 ± 530, 3999 ± 099 kg, the 305-day milk yield as 4920 ± 217, 4462 ± 900, 4635 ± 870 kg, the lactation period as 222 ± 36, 240 ± 04, 258 ± 37 days, the daily milk yield as 17.62 ± 2, 15.49 ± 2, 16.04 ± 3 kg for AA, AB, and BB genotypes, respectively. In the statistical analyses, the relationships between the performance traits studied and Pit-1 genotypes in Simmental and Brown Swiss cattle were not prove to be significant statistically.