Background: In rheumatoid arthritis, your immune system attacks the tissue lining the joints on both sides of your body. Other parts of the body may also be affected. Unsure of the exact cause. Two separate genes termed IL12A (p35) and IL12 encode the heterodimeric cytokine known as IL12 (p40). Several different hematopoietic cell types can have several different hematopoietic cell types that can generate antigen-presenting cells (APCs), including DCs and macrophages. Objectives: This study aimed to investigate if the interleukin IL-12B gene's common polymorphisms in an Iraqi population were associated with RA. Material and methods: Blood samples were taken from 70 Iraqi patients with RA illnesses and 30 Iraqi controls during the periods from April 2022 to June 2022 at Baghdad Teaching Hospital and Typical Rheumatology Unit. IL-12 level was determined by ELISA, and the IL-12B gene SNP was investigated through RT-PCR. Results: Between the sick and the healthy group, there was no statistically significant difference in the levels of IL-12. The allele G was more prevalent, and the genotype GG was more noticeable in patients compared to healthy people. As a result, the pattern represents a risk factor for RA (OR (95% CI, 1.55, (0.47 - 5.12), P=0.523). Conclusion: We concluded that the IL-12B gene SNP rs3212227 GG was linked to the onset of RA, and that people carrying the G allele had a greater probability of doing so.