The results of the study of the genetic characteristics cows of the breed of Sychevka in the breeding plant KP "Rybkovskoe" of the Smolensk region with a lifetime productivity of up to 25,000 kg of milk (group I) and with a lifetime milk yield of 45,000 kg or more of milk (group II) are presented. It was found that the groups have some genetic features for EAB-alleles. The index of genetic similarity between the groups is 0.538. In the first group, 56 EAB alleles were identified, in the second – 46. The frequency of occurrence of the main alleles in the groups is 0.763 and 0.774. Among them, five marker alleles are found with a high frequency of 0.44 – 0.116. Alleles of the EAB locus b, A1B/, B1G2O1, O1Y2E/3G/G//, O2A/2J/2K/O/, Q/ are more common in high-yielding cows by 2.5 – 7.2 %, and the EAB alleles B2O1, O/, E/3G/G// are not found or are less common. When comparing the productivity of cows with different EAB – alleles, differences were noted. Lifetime productivity in cows with EAB alleles O1, I1Y2E/3G/G//, O2A/2J/2K/O/, I2, A/1B/ is higher than in cows with EAB alleles E/3G/G//, BI1Q, Y1A/1, I1Y2I/. There is a significant difference in the duration of use in cows with the EAB-alleles O1, O1Y2E/3G/G//, O1I/Q/, I1O2A/2K/Q/. There were no significant differences in the content of fat and protein in milk.