Chronic hepatitis C virus (HCV) infection is an important public health issue. Globally, the estimated prevalence of hepatitis C virus infection is about 3% where Egypt is the country with the highest HCV prevalence in the world. Interferon based therapies are the leading therapeutic regimens to hepatitis C infection worldwide. Different regimens of IFN therapy have variable response rate as sustained virological response (SVR), relapser (response and relapse) (RR) or breakthrough (BT), and non-response (NR). Combination therapy of interferon and ribavirin or pegylated interferon had significant beneficial effects on virological markers and histological response. On the other hand, the combination therapy increased the risk of hematological, dermatological and miscellaneous adverse events. The chronic hepatitis C treatment efficacy is determined by many viral and host factors. From these factors we choose the IL-1O to study its role in the response to the treatment because of itspleotropic effect on the immune system.