Several studies indicate that chemokines play important roles in colorectal mucosal immunity by recruiting leukocytes into and out of the lamina propria adjacent to the epithelium. The chemokine CXCL5 which is expressed by epithelial cells within colorectal mucosa is a chemoattractant for neutrophils and has been implicated in Crohn's disease and ulcerative colitis. In addition, CXCL5 is one chemokine which promote angiogenesis related to cancer. The objective of this study was to determine by ELISA assay whether CXCL5 protein level is altered in colorectal cancer (CRC) tissues (n=80) compared with paired normal mucosa. Furthermore, the plasma CXCL5 levels from CRC patients (n=62) compared with controls (n=71) were also examined. Using a TaqMan system we screened for -156G--> C and +398G-->A CXCL5 gene variants in CRC patients (n=228) and a control group (n=231) to assess the role of CXCL5 genotype in CRC. The analyses showed that CXCL5 protein level in colorectal tumours was significantly (P<0.0001) higher than in normal tissue and was lower in plasma in CRC patients compared with controls (P=0.026). Immunohistochemistry revealed CXCL5 immunoreactivity mainly in epithelial cells of the colorectal carcinoma and in normal epithelial cells. Furthermore, patients who were -156C carriers had higher CXCL5 protein concentration compared with -156G carriers in normal tissue (P=0.027) and CXCL5 protein levels in cancerous tissue tended to be higher for the patient -156C carriers (P=0.059). To our knowledge this is the first report on the influence of CXCL5 gene variants and their relation to expression of CXCL5 protein in human CRC.