The effect of host genetic variation on the outcome of hepatitis C virus (HCV) infection and its treatment is poorly understood. The chemokine receptors CCR5, CCR2, and CCR3 and their ligands, RANTES, MCP-1, MCP-2, and MIP-1␣, are involved in the immune responses and the selective recruitment of lymphocytes to the liver in HCV infection. We studied 20 polymorphisms within these genes and investigated their association with persistent carriage of HCV, severity of liver disease, hepatic inflammation, and response to treatment in a large European cohort. Significant associations were found between CCR5-⌬32 and reduced portal inflammation (P ؍ H epatitis C virus (HCV) is a major global health problem with 1% to 2% of the world's population chronically infected. The prevalence of infection in the United Kingdom is approximately 0.5%, 1 but it is likely that this figure will continue to rise as more cases come to light. Persistent HCV infection has a very variable outcome, with 25% of those infected developing cirrhosis within 20 years, of whom 3% to 5% per year will proceed to hepatocellular carcinoma. A further 5% per year will develop liver failure, and 2% per year will die of a liver-related death. There is also a very variable response to treatment because only 40% of those treated with interferon alfa and ribavirin successfully clear the virus. 2,3 There are a number of epidemiologic and viral factors that influence susceptibility to persistent HCV infection, progression of HCV-related liver disease, and response to treatment, but host genetic factors are also influential. This study has examined 20 polymorphisms in the genes for the CC chemokine receptors (CCR) CCR5, CCR2, and CCR3 and their ligands, RANTES (regulated and normal T-cell expressed and secreted), MCP-1 (monocyte chemotactic protein), MCP-2, and MIP-1␣ (macrophage inflammatory protein), to try and elucidate their role in the immunopathologic outcome of HCV infection..Chemokines constitute a large family of small (8-10 kD) cytokines that are up-regulated in inflammation and whose effects are mediated by members of a family of 7 transmembrane domain, G protein-coupled receptors. 4 Their major role is in leukocyte migration and dependent processes such as immune surveillance and innate and adaptive immune responses. Chemokines have been