Chronic alcoholism in patients with chronic hepatitis C appears to cause more severe and rapidly progressive liver disease leading more frequently to cirrhosis of the liver and hepatocellular carcinoma. The primary risk factor for acquiring hepatitis C among alcoholics is injection drug use. However, the epidemiology is not well defined, and other sources of spread must be important. Alcohol intake in excess of 10 g/d has been associated with increased serum hepatitis C viral RNA and aminotransferase levels, the mechanism of which is poorly understood. The histological picture of hepatitis C in patients with chronic alcoholism is typically indistinguishable from chronic hepatitis C in nonalcoholic patients. Interferon therapy is less effective among alcoholic than nonalcoholic patients, even after a period of abstinence. Patients with chronic hepatitis C should restrict their alcohol intake to less than 10 g/d, and if cirrhosis is present or interferon therapy is planned, abstinence from alcohol should be encouraged. Future research efforts should focus on the epidemiology and pathogenesis of combined chronic hepatitis C and alcoholism.