Excess alcohol consumption can worsen the course and outcome of chronic hepatitis C. It is important to distinguish between alcohol abuse, which must be treated on its own merits, and the effect of alcohol use on progression, severity, and treatment of hepatitis C. Most studies on the effects of alcohol on hepatitis C have focused on patients with high levels of daily alcohol intake. Indeed, the adverse effects of light and moderate amounts of alcohol intake on hepatitis C virus (HCV) infection have not been clearly shown, and only limited studies have been performed. Sex differences exist in the effect of alcohol on fibrosis as well as on the severity of hepatitis C. Alcohol use has been reported to be associated with lower responses to therapy and, in some studies, higher HCV RNA levels and increased HCV quasi-species. Few studies address the treatment of hepatitis C in the alcoholic individual or determine the effect of continued light or moderate alcohol use on the outcome of treatment response. In summary, many critical questions remain regarding the interactions between alcohol and hepatitis C. Currently, the evidence from the literature shows that heavy alcohol intake worsens the outcome of HCV infection. The literature is inadequate to provide definitive recommendations regarding the effect of light to moderate alcohol use in patients with hepatitis C.