Abstract <p>To increase the meat productivity of sheep breeds, identification of markers in the genes associated with muscle tissue development is used. The <i>RIMS2</i> gene in various genome-wide association studies was indicated as a candidate gene associated with meat productivity parameters. We conducted whole-genome DNA sequencing of Manych Merino rams, allowing us to study the structure of the <i>RIMS2</i> gene. This resulted in the identification of over 12 000 polymorphic variants. The association of these structural variants with live weight was studied in Manych Merino rams. Among them, 191 loci were identified that were significantly associated with differences in this parameter between carriers of different alleles. Based on the analysis, we identified seven intronic polymorphisms on the chromosome 9 that showed the greatest difference in the average weight at positions 73 649 784, 73 649 844, 73 650 396, 73 656 001, 73 649 505, 73 653 951, and 73 564 014. All of them are located in introns and are single nucleotide polymorphisms (SNPs). The presence of substitutions 73 649 784, 73 649 844, and 73 650 396 was associated with an average live weight of animals, which was 11.14 kg (27.6%) greater as compared with reference homozygotes. Homozygotes for the substitution at position 73 564 014 had an average body weight 21.5% greater than that in carriers of the reference variant. Conversely, SNPs 73 656 001, 73 649 505, and 73 653 951 were present in animals with this index 25–27.5% lower as compared with carriers of the reference variants. Therefore, the <i>RIMS2</i> gene contains polymorphic variants significantly associated with the live weight parameter in Manych Merino sheep breed. Subsequently, they can be used as molecular markers in breeding for improved meat productivity. Further study of the <i>RIMS2</i> gene is needed to establish the precise mechanisms, by which it influences the muscle growth and development.</p>