The current meta-analysis was employed to combine the results of multiple studies into a single estimate related to B-LG, CSN3, DGAT1, PRL, GH, and PIT1 gene polymorphisms and their effects on milk production traits. The purpose of this meta-analysis was to investigate associations between B-LG, CSN3, DGAT1, GH, PIT1, and PRLgene polymorphisms with milk production traits in Holstein dairy cows. An extensive search was done from 2002 to 2022 year. Statistical analyses were performed by using Stata 11.2 software. Genetic models viz codominant (AA vs. AB, AA vs. BB, and AB vs. BB), dominant (AA + AB vs. BB), recessive (AA vs. AB + BB), and completely over-dominant (AA + BB vs. AB) were applied. The results of meta-analysis of association between B-LG genotypes with milk yield where found a significant (P <
0.05) and with fat and protein contents (P <
0.01). In CSN3 polymorphisms of A/A and A/B genotypes had a significant effect on fat yield (P <
0.05) and protein content (P <
0.01). DGAT1 polymorphisms had a significant effect on milk yield, fat yield, protein yield (P <
0.05), with fat and protein contents showed high effect (P <
0.01). No significant association was detected between GH and milk traits (P >
0.05). PIT1 genotype polymorphisms had a significant effect on milk yield (P <
0.05) and protein content (P <
0.01). PRL genotype polymorphisms were significantly associated with milk yield (P <
0.05), fat content and protein yield (P <
0.01). The B-LG, DGAT1,CSN3 and PRL gene polymorphisms could be utilized as good markers to improve milk production traits in the Holstein cattle breed.