<b>Molecular genetic aspects of the POU 1 F 1 gene in Holstein reproductive traits</b> The development of DNA technologies within the framework of the concept of gene marker selection allows us to evaluate animals by allelic variants of genes, directly or indirectly related to productive features. The authors study the polymorphism of the POU1F1 gene and its relation to the milk productivity of Holstein breed cows. As part of the study the samples of biological materials were taken from 50 animals, commercial sets were used to isolate genomic DNA, and polymorphism was analyzed according to a standard procedure. The results of the studies showed that the polymorphism of the POU1F1 gene has a significant effect on the average daily yield of milk yield and milk yield for 305 days of lactation in Holstein breed cows. The authors also found out that alleles, but not genotypes, have the greatest influence on the symptoms. The conducted studies allow to suggest that the diagnosis of allelic variants of the POU1F1 gene can be used in practical work to select heifers genetically predisposed to the highest milk yields. Holstein breed, POU1F1 gene polymorphism, milk productivity 2567-2570 Issue-3 Volume-2 Ward M. Ashraf | Abuargob M. Omry | Hdud M. Ismail | Elgusbi M. Tarek | Ruban Y. Sergey