Abstract:[Objective] To explore the relationship between frozen shoulder (FS) and gene polymorphism of IL-1β and interleukin-1receptor antagonist (IL-1Ra). [Methods] From January 2021 to August 2023, 225 patients who were treated in our hospital were selected asthe frozen shoulder group, while other 275 normal persons as the normal group. The genotypes of the two groups in IL-1β gene loci were de-tected by polymerase chain reaction and restriction fragment length polymorphism. The correlation between the haploids and the risk rate offrozen shoulder disease was analyzed. In addition, the correlation between different genotypes of interleukin-l receptor antagonist allele*2,(IL-1RN) and the susceptibility to frozen shoulder disease was also analyzed. [Results] Compared with wild-type CC (non-mutated geno-type), patients with heterozygous CT genotype (mutated genotype) had a significantly higher risk of FS (OR=1.952, 95%CI 1.142~3.320, P=0.014). The C gene at the IL-1B+3954 locus may be a protective gene, and the risk of FS in the C gene was significantly reduced at the IL-1B+3954 locus (OR=0.577, 95%CI 0.309~0.987, P=0.049). The risk of FS for CT genotype at IL-1B-31C/T locus was significantly higherthan that for TT genotype (OR=1.791, 95%CI 1.171~2.742, P=0.004). Haplotype analysis found that haplotype TTT was more strongly asso-ciated with a higher risk of FS than the most common CCT haplotype (OR=7.100, 95%CI 1.492~33.870, P=0.014). Unconditional Logisticregression analysis showed that there was no statistically significant difference in the distribution of four genes of IL-1RN (VNTR) betweenthe two groups (P=0.521), and the risk of FS in the IL-1RN variant group (1/2 and 2/2) was 1.895 times higher than that in the non-variantgroup (1/1, 1/3, 1/4), whereas which was not statistically significant (P>0.05). [Conclusion] CT genotypes of IL-1β gene rs1143627 andrs1143634 were associated with susceptibility to frozen shoulder in frozen shoulder group. Haploid TTT formed by three gene loci may in-crease the risk of frozen shoulder, and no susceptibility genotype for frozen shoulder was found in IL-1RN.