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Behcet's disease (BD) is a systemic vasculitis, characterized by recurrent oral aphthous, genital ulcers, ocular lesions, and other organ involvement. Interleukin (IL)-27 with its pro- and anti-inflammatory effects might be an important effective cytokine in this disease. The aim of this study was to investigate the association of IL-27 serum concentration and a single-nucleotide polymorphism (SNP) rs153109 (-964 A > G) with the risk and clinical features of the patients with BD. IL-27 Genotyping was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and the IL-27 serum levels were measured using enzyme-linked immunosorbent assay (ELISA). It is shown that AG, GG, and AG + GG genotypes, as well as G allele of rs153109, can significantly increase the risk of BD in total and in male individuals. Significantly higher frequencies of AG and GG genotypes and G allele were observed in total and male patients with an active form of BD. AG and GG genotypes were associated with joint (p = 0.046) and vascular (p = 0.02) involvement. The frequency of the G allele was higher in all patients, as well as in female patients with vascular involvement (p = 0.02). Serum cytokine analysis indicated an increased level of IL-27 in BD patients compared to healthy subjects (p = 0.038). Additionally, a higher level of IL-27 was detected in patients carrying the rs153109 GG genotype (p = 0.04) and those with renal (p = 0.009) and skin (p = 0.05) involvement. In conclusion, this study underscores the involvement of IL-27 rs153109 variants and increased serum level in BD susceptibility and pathogenesis.