©Copyright 2014 by Gazi University Medical FacultyObjective: Chronic HCV infection is a dynamic state of the interactions between virus and host immune response, and the natural course varies greatly among different individuals. So currently, most studies investigating the underlying mechanisms of HCV infection have focused on genetic variations in the human population. Specially, polymorphisms of immune response genes may be considered related to a genetic susceptibility to HCV infection. IL18 is a proinflammatory cytokine that plays an important role in the Th1 response. IL18 gene has two polymorphisms (-137 G/C and -607 A/C) within the promoter of the gene have been associated with different inflammatory and autoimmune diseases. However, there are a few study whether IL18 polymorphisms have influence on host immune response to HCV infection. The aim of the present study was to determine whether IL18 promoter polymorphisms association with chronic HCV infection in Turkish subjects. Method: To evaluate the role of host IL18 -607C/A (rs1946518) and -137G/C (rs187238) polymorphism in predicting HCV infection, IL18 gene polymorphisms were studied in 63 hepatitis C patients and 65 control subjects by using the PCR-RFLP method. Results: No significant differences were observed in genotype or allele frequencies among chronically HCV-infected and healthy subjects. Conclusion: Our results suggest that the IL18 gene polymorphism is not a major factor predisposing to the development of chronic Hepatitis C infection.