Infection with hepatitis C virus (HCV) accounts for 40% of cases of chronic liver disease in the United States and is now the most common indication for liver transplantation. Estimates suggest that 4 million people (1.8%) of the American population are or have been infected with HCV. Currently, the treatment of choice for patients with chronic HCV infection is recombinant interferon alfa with ribavirin. Pegylated interferons are a promising new development, and in combination with ribavirin, they will rapidly become the standard of care. The goals of therapy are to slow disease progression, improve hepatic histology, reduce infectivity, and reduce the risk of hepatocellular carcinoma. Sustained virologic response, which generally implies the absence of viremia for 6 months or more following completion of therapy, is increasingly being regarded as a cure, with evidence of slowing or even regression of fibrosis on follow-up liver biopsy. A number of factors have been shown to be predictive of a sustained response, including viral genotype other than 1, low serum HCV RNA levels, absence of cirrhosis, younger age, female gender, and shorter duration of infection. Disease severity as assessed by liver biopsy, comorbidities, and possible contraindications to therapy should be weighed in the decision to begin treatment. Counseling patients regarding transmission, natural history, and drug and alcohol abstinence also should be included in management. Close monitoring should be done during treatment for side effects of interferon, including depression and bone marrow suppression. Hemolytic anemia is the major side effect of ribavirin.