Behçet disease (BD) is a chronic, multisystemic disease characterized by relapsing episodes of a wide spectrum of clinical symptoms. Several genetic and immunological factors have been suggested to be involved in the aetiopathogenesis of BD.To investigate the association between BD and five single nucleotide polymorphisms (SNP) in the gene for interleukin (IL)-23 receptor (IL-23R).We recruited 123 patients with BD and 168 controls. A detailed phenotypic investigation of BD was made for each patient. Five SNPs in the IL-23R gene (rs11209026, rs7517847, rs11805303, rs1004819, rs17375018) were investigated.We found that patients with BD had a lower frequency of the rs17375018 GA and AA genotypes, and a higher frequency of the rs17375018 G allele, and these were statistically significant. The rs11209026 G allele frequency was higher in male patients with BD than in male controls, and the rs7517847 G allele was higher in patients with genital ulcers. The rs11805303 G and rs1004819 G alleles were more frequent in patients with papulopustular lesions.The rs17375018 variant in the IL-23R gene seems likely to be a strong susceptibility factor for BD in the Turkish population. As this variant was also shown to have a higher frequency in BD patients from different ethnic backgrounds in two previous studies, it may be specific for BD.