Background and aims: CXCL16 is a scavenger receptor which has been connected to phagocytosis of bacterial antigens in experimental colitis. It has also been shown to have a pivotal role in the development of experimental colitis in mice. The increased expression of CXCL16 has been demonstrated in inflamed lesions of patients with Crohn disease. Our aim was to study the expression of CXCL16 in the colon of patients with ulcerative colitis. Methods: Relative quantitative reverse transcription-polymerase chain reaction was applied to explore the gene expressions of CXCL16, its receptor CXCR6, and interleukin 8, an inflammatory marker, in the colonic biopsies of children with active ulcerative colitis (n = 19), children with ulcerative colitis in remission (n = 9) and children with no inflammatory condition in colon (n = 14). Results: An increased expression of CXCL16 in the colonic biopsies of children with ulcerative colitis was found both in active disease (p = 0.006) and in remission (p = 0.033), when compared to children without inflammatory condition. The gene expressions of interleukin 8 and CXCL16 correlated with each other (r(s) = 0.67, p = 0.01). The expression of CXCR6 mRNA was comparable between the study groups (p = 0.50). Conclusions: The gene expression of CXCL16 was increased in patients with ulcerative colitis both in active disease and in remission suggesting an important role of the molecule in the pathogenesis of the condition. (C) 2014 European Crohn's and Colitis Organisation. Published by Elsevier B.V. All rights reserved.