AIM To investigate the association of seven single nucleotide polymorphisms(SNPs) of the IL23 R gene with the clinical picture of ulcerative colitis(UC). METHODS Genomic DNA samples of 131 patients (66 males, 65 females, mean age 55.4 ± 15.8 years) with Caucasian origin, diagnosed with UC were investigated. The diagnosis of UC was based on the established clinical, endoscopic, radiological, and histopathological guidelines. DNA was extracted from peripheral blood leukocytes by routine salting out method. Polymerase chain reaction and restriction fragment length polymorphism were used to identify the alleles of seven SNPs of IL23 R gene(rs11209026, rs10889677, rs1004819, rs2201841, rs7517847, rs10489629, rs7530511).RESULTS Four out of seven analyzed SNPs had statistically significant influence on the clinical picture of UC. Two SNPs were associated with greater colonic extension(rs2201841 P = 0.0084; rs10489629 P = 0.0405). For two of the SNPs, there was more frequently need for operations (rs2201841 P = 0.0348, OR = 8.0; rs10889677 P = 0.0347, OR = 8.0). The rs2201841 showed to be a risk factor for the development of iron deficiency (P = 0.0388, OR = 6.1837). For patients with the rs10889677, a therapy with azathioprine was more frequently necessary(P = 0.0116, OR = 6.1707). Patients with rs10489629 SNP had a lower risk for weight loss(P = 0.0169, OR = 0.3394). Carriers of the heterozygous variant had a higher risk for an extended disease (P = 0.0284). The rs7517847 showed a protective character leading to mild bowel movements. Three SNPs demonstrated no statistically significant influence on any examined clinical features of UC.CONCLUSION We demonstrated susceptible or protective character of the investigated IL23 R SNPs on the phenotype of UC, confirming the genetic association. AIM To investigate the association of seven single nucleotide polymorphisms (SNPs) of the IL23 R gene with the clinical picture of ulcerative colitis (UC). METHODS Genomic DNA samples of 131 patients (66 males, 65 females, mean age 55.4 ± 15.8 years) The diagnosis of UC was based on the established clinical, endoscopic, radiological, and histopathological guidelines. DNA was extracted from peripheral blood leukocytes by routine salting out method. Polymerase chain reaction and restriction fragment length polymorphism were used to identify the alleles of seven SNPs of IL23 R gene (rs11209026, rs10889677, rs1004819, rs2201841, rs7517847, rs10489629, rs7530511) .RESULTS Four out of seven analyzed SNPs had significant significant influence on the clinical picture of UC. Two SNPs were associated with greater colonic extension (rs2201841 P = 0.0084; rs10489629 P = 0.0405). For two of the SNPs, there was more frequently need for oper The rs2201841 showed to be a risk factor for the development of iron deficiency (P = 0.0388, OR = 6.1837). For patients with the rs10889677 (rs = 0.0388, OR = Patients with rs10489629 SNP had a lower risk for weight loss (P = 0.0169, OR = 0.3394). Carriers of the heterozygous variant had a higher risk for an extended disease (P = 0.0284). The SN7517847 showed a protective character leading to mild bowel movements. Three SNPs demonstrated no significant significant on on any examined clinical features of UC. CONCLUSION We demonstrated susceptible or protective character of the investigated IL23 R SNPs on the phenotype of UC, confirming the genetic association.