Hepatitis C is a heterogeneous disease and is responsible for considerable mortality and morbidity. The hepatitis C virus (HCV) infects nearly 170 million people world-wide. More than 80% of infected individuals develop chronic infection; the remaining 10-20% develop spontaneous clearance with natural immunity. Acute hepatitis is icteric in only 20% of patients and is rarely severe. The majority of patients who develop chronic HCV infection are asymptomatic; but 60-80% develop chronic hepatitis as indicated by elevated alanine aminotransferase (ALT), around 30% maintain persistently normal ALT levels despite having detectable HCV-RNA in serum. One-third of chronically infected patients develop progressive liver injury, fibrosis and cirrhosis over a period of 20-30 years. The relationship between virus load, HCV genotype, quasi-species variability and progression of liver disease is controversial. Acquired infection after age 40, male sex, excessive alcohol-consumption, hepatitis B virus (HBV) or HIV co-infection, steatosis, and immunosuppressed state have been identified as co-factors associated with progression of fibrosis and development of cirrhosis. In patients with cirrhosis, the incidence of hepatocellular carcinoma is 2-5% per year. At present, HCV-related end-stage cirrhosis is the first cause of liver transplantation.