Several epidemiological studies suggest that chronic alcoholics are at risk of viral infections. Clinical and basic research has demonstrated that alcohol not only worsens the natural history of chronic viral hepatitis, but also seems to interact with the viral replication cycle leading to an unusual serum virological profile and/or modification in the serum concentration of viral particles. Infections with hepatitis B and C viruses are a major risk for the development of hepatocellular carcinoma in excessive drinkers who should be protected against these viruses.